Automatic CPU speed & power optimizer for Linux based on active monitoring of laptop's battery state, CPU usage, CPU temperature and system load. Ultimately allowing you to improve battery life without making any compromises.

Homepage: https://github.com/AdnanHodzic/auto-cpufreq
Why: Because Linux battery life on laptops is pure pain & this package is so good that for laptops It's a must have.
Now it's You can install this from command line but it's not gonna auto update & for ,,basic" users it's not easily accessible.
Open Source: Yes(?)
Ver. source: https://github.com/AdnanHodzic/auto-cpufreq/archive/refs/tags/v1.6.4.zip

It will probably require a bit of config for Solus. I'm using this on my Chromebook (installed via command line installer) & it really helps when it comes to heat (my machine is overheating by design...) & battery life - machine lives longer if I don't watch movies. When I watch movies it lives shorter as It should.