If you need more Linux testers using various distributions you can open a newsletter / form or something and start seeing if you gather enough people to consider it satisfying. I’ll be glad to subscribe.
In my experience Godot Linux export is quite reliable (second after Renpy in terms of “just build blindly on Windows, macOS and Linux and if one platform works, all 3 probably do”, certainly thanks to the use of export templates), but I’ve mostly been using Godot 4 lately so that’s probably something works checking after the Godot 4 port (but you can start the newsletter / subscribe form already to start gathering people).