Linux

Kali isn't meant to be a desktop OS. Use it only in VM or in a spare rig. It is meant to be a toolbox. So dual boot it with your daily driver OS or use in a VM.

Your Mac can take Linux just well: https://djharper.dev/post/2020/06/07/running-linux-on-my-macbook/

For your 300 bucks budget look nothing else than Thinkpad T480 or HP Dev One. T480 will need replacement batteries if not replaced yet.

I think my next one will be a https://frame.work There is also an overview of supported systems: https://frame.work/en/en/linux

For under $300, I would go for a used Thinkpad. I got a T460s for a few hundred bucks that runs linux wonderfully (jesus was the pre-installed Windows slow though). Linux usually runs much better than Windows on old low-end hardware. That 2015 MacBook has an Intel processor, so I would try Linux on that first as it might be more powerful than what you can afford to buy.

Kali is not an OS you would want to use for your main desktop, if you need those security tools you can run them in a virtual machine / live usb. I see you've tried to base your distro choice off of what you intend to do in school, which I think is a mistake. Choose your distro based off of the merits of the distro itself, as once you get past the package manager and release cycle, you can get the same experience on any distribution.

Before choosing a distro I would make sure you know the answer to these questions (in terms of what you want):

1. Stable or rolling release model?
2. Package manager (apt, dnf, pacman, zypper, etc.)

and these about your desktop environment:

3. What desktop environment (or standalone window manager) do you want to use?
4. Do I want to use Wayland or X11 as a display server? Does it matter to me which I use?
5. Does your distro have a spin preinstalled with your desktop environment of choice?

^ Also, if you are unsure about what some of this means, feel free to ask.

Interested in Linux? Getting a degree in Cyber Security?

A used ThinkPad. The older the better

Purchase an extra memory stick for your existing laptop and run your tools on a virtual machine. Very few utilities require an physical machine.

Edit: MBP 2015 is not memory upgradable. But I believe my statement is still your best option.

whatever you get, don't sleep on the ethernet port, very few cheap laptops come with it nowadays, and that ill greatly reduce your selection

Thinkpad for compatibility

Your best bet is probably to get a refurbished thinkpad. I've seen X1 Carbons (their ultra thin Macbook-like line of ultrabooks) for 250 bucks on backmarket. That's the 2016 model (G5) and not in the best tier of refurbishment (So there might be some small scratches on the chassis) but the hardware should be more than enough for your usecase. Linux generally speaking does very well on low end hardware and thinkpads are especially well supported.

One thing though: DON'T INSTALL KALI ON YOUR DEVICE, IT'S NOT DESIGNED FOR THAT. Or rather it wasn't. Originally Kali was meant to be run of a thumb drive only. By now enough people have attempted to install it that the devs have given up and provide a bare metal edition. That is just Debian with some stuff preinstalled though. There is very little secret source (like the "undercover mode"). You should go with debian and try to build your toolbox as you go. This way you will get a better insight into your Linux system because it forces you to set up everything yourself

I have a cheap Acer laptop with AMD and it works great. I'm dual booting with Windows. I do remember having to struggle with the install though. I had to turn off secure boot and can't remember what else. Good luck.

Anything that doesn't have an NVIDIA GPU is Linux-friendly.

My t480 came in right at that price, and is doing very well for word processing and media consumption.

But Linux is almost always going to do well on low end stuff compared to Windows.

Tuxedo is the linux brand of the german company "Schenker".

If you're trying to optimize your cost, you might get away for free by installing a virtual machine on your existing MacBook :)

I've always stuck to Thinkpads for Linux -- especially the T series is incredibly solid. That said, you really shouldn't have an issue with a 2015 MacBook.

does Linux run fine on low-end laptops?

Linux runs fine on a potato lol

Currently I think the most eco-friendly option is a Framework.

I am running Fedora Asahi Linux on my M1 MBA and it performs fantastically.

I'd check local places like offerup. can get business laptops for cheap when places refresh. there are a few people around me selling 3-4 year old dells with i5/i7, nvme, etc. take a Linux USB and install it on site before you buy to test. they're more than enough specwise for daily use or testing. often sub $300

With that budget you should be able to get your hands on a machine with plenty of power. My recomendation would go to a lenovo t480/t480s. I was planning to buy one of those for myself but my current laptop is still good enough. Regardless of the device you choose, I would recomend portability over power: power efficient i5 4 cores, 8gb (idealy 16gb) ram, ssd storage, lightweight and good battery.

To answer your last question, you shouldn't be concerned about performance. Linux can give life to old hardware, but you're not really looking at old hardware.

As a cybersec student myself, I would suggest starting out with a generic linux distro and just install the tools you need as you go. If you really need kali, install it in a vm. I say this because I expect you'll use Linux as your daily driver, and Kali is NOT mean to be a daily driver, but a tool for when you need it. And "when you need it" will come with experience I guess.

Definitely the framework laptop, check it out, it's completely modular, thin, light, performant, and insanely repairable, they even include qr codes on every part to help replace them and they will ship the device to you with no os for a discount and disassembled for a much bigger discount.