Is this game still in development or the maker(s) just focus on Strive 2 and here and there release some bugfixes for this one?
Strive 1 is considered complete, as there is no more planned content for the game and most of the developer's time is going towards Displaced and Strive 2. All changes at this point are community driven in the forms of patches and mods. For example, redle's gui mods inspired the dev to incorporate some of his idea's for version 0.5.25. I have a bugfix patch on the Strive Discord(https://itch.io/t/284398/discord) #mods channel, which may be added to the official release at some point, but I am working on adding some more fixes at the moment.
to be fair:
https://strive4power.itch.io/strive-sequel-demo
demo had public release, have fun