First of all i have no problem with FreeBSD. Just, why BSD? What is Linux not enough for you? Why not Devuan? What is the difference between Devuan and FreeBSD? Is the code environment different? Completely different things...
I guess I'll attempt to bite this one as I have nothing better to do right now, kinda'....
This question could have a million different answers. I could ask the same thing of you. Why Devuan? Why not Debian? Why not Ubuntu? Why not somewhatevernonamedistro?
I still don't know if I should choose FreeBSD or Devuan.
That's the mystery. Quite the dilemma we have here.
1. I don't like to play games, but occasionally I play Assetto Corsa and ETS2. Apparently, Steam-Proton support is zero.
Well, if you don't like to play games, you probably wouldn't play any games. Clearly, you like them at least a little bit. It seems like you may not know yourself as well as you thought you did.
2. How is the init system? I'm using Runit from Linux and it's pretty fast. I want to see which init is in FreeBSD. I can also say that I am obsessed with the init system.
Init system uses ngInit. I don't get the obsession with the init system.... but I'm not going to ask.
3. Can Linux programs be run? Here are all the programs I use:
-i3 gaps
-neovim
-lf file manager
-steam
-bottles/wine
-open/libre office
-obs
-kdenlive
-shotcut
-irfanview
-polybar
-open dicom viewer
-tor browser
-qute browser
-firefox
-gimp
I don't know if their ports or packages are available on FreeBSD.
I don't use all of those, but I have used a fair bit on that list. I wouldn't be surprised if all of them are in the ports tree.
4. How is the package management? Can I run .deb packages? Are there some kind of package managers like Linux? Is there flatpak support?
pkg is solid. You can probably run a lot of deb packages on the Linux compatibility layer, but it could be a hit or miss.
As for Flatpak, I haven't tried, but probably not. Why would you want to use Flatpak anyway? You mentioned Devuan and "obsession" on Init system... I'm guessing it's not obsession, but rather hate on systemd bandwagon. In which case, you probably should also not like Flatpak as it introduces a lot of bloat and potentially a lot of redundant libraries... kinda' like systemd in a way.
5. How is the hardware and driver support? Here are my system specs:
-Ryzen 3600
- GTX 1660ti
-B550 Gigabyte
-Samsung NVMe
Only potential problems here are probably the GPU and the chipset. I don't have the GPU so can't comment on it, but I do have the chipset. I think the only problematic thing is the bluetooth/WiFi chip.
6. Is there GPT/UEFI support?
Yes.
7. If I install 2 operating systems at the same time, how will I manage the other with FreeBSD?
Probably grub or even just straight UEFI boot.
8. Are GNU tools available?
Yes.
9. Is the learning curve difficult? It's not hard, I want simple. (like Devuan)
There is some learning curve, probably more so than your average Linux, but the handbook should help with most issues.
10. Is there support for Wayland and XWayland?
Yes.