It is not listed in F-Droid. Maybe they will do it in the future, that is currently the only issue on GitHub https://github.com/chenxiaolong/RSAF/issues/50. Until then, you could use Obtanium.

Azimuth

Azimuth is a metroidvania game, and something of an homage to the previous greats of the genre (Super Metroid in particular). You will need to pilot your ship, explore the inside of the planet, fight enemies, overcome obstacles, and uncover the storyline piece by piece. Azimuth features a huge game world to explore, lots of little puzzles to solve, dozens of weapons and upgrades to find and use, and a wide variety of enemies and bosses to tangle with.

It is open source and available for Windows, macOS, and Linux.