I don't have any suggestions. I can't think of any proprietary app good enough that I'd give up control of my computing for. However, consider objective requirements rather than subjective terms like good. What do you use the proprietary app for, why are existing free alternatives not sufficient, and can a free app be made that satisfies those requirements?

I'd be happy if Voiply would just work without GMS and could be downloaded from F-droid.

File Explorer

I haven't checked in a while, but I am still using CX File Explorer because I didn't find a FOSS alternative I like. Maybe it is just because I am used to it, but one thing I really like is the network feature that you can access local shares of a NAS.

This is not an answer to your question, but I would love if somebody would make InputStick software for platforms other than android if possible

It’s not an Android app but ServerCat is the best multi device monitoring/ssh software for mobile that I’ve come across. Sadly none of the alternatives on iOS or Android compare. Totally room for a proper competitor that fits a lot of information in an intuitive and clean ui.