Perhaps first hit on google is better? ;). Source: about 2 years ago

While I can't speak for how this information could be abused on platforms like mobile, the APIs used for battery reporting (amongst other things) is done via UPower. What you are seeing here is some weird reporting by slick-greeter (not developed by Solus) on the battery percentage level. Source: over 2 years ago

There's a way of doing it via s-tui. Source: about 1 year ago

I don't know about fan speeds, but there is a good Linux tool for testing throttling, namely, 's-tui'. The program can be a pain to install. Here is how I did it (and this method installs the program as root, which in this case is good because some of the program's feature's need root access). Source: almost 3 years ago

I would check out https://github.com/aristocratos/bashtop, and https://amanusk.github.io/s-tui/ for inspiration! Source: about 3 years ago