Various options:
- Raspberry Pi. However, although it can handle a lot of selfhosted stuff, some things won't be fast. Especially wazuh or nextcloud may be problematic. Also you are limited by ARM architecture and the price is not that beneficial anymore
- Some small form factor (SFF) servers from eBay. Something like Lenovo ThinkCell Tiny or Dell Optiplex Micro. As you will have a second NAS for storage, it will be fine that you can only put 1 HDD/SSD into those models
- A NUC from Minisforum. More pricey but new and plenty of power. Runs with 10W idle. I rock the HM90 EliteMini with 2 SSDs and one onboard NVME for proxmox as hypervisor OS.
Ensure to choose wisely. Especially regarding power consumption and hardware encoding capabilities (Looping at you jellyfin).
Otherwise, some summarized infos here:
https://blog.lrvt.de/homelab-server-recommendation/
BTW: I do not recommend running a Tor exit node.