Yeah, you don’t even have to jailbreak it, you can just install it alongside the kobo software, then you can keep both. It’s a bit fiddly to set up but not too bad https://github.com/koreader/koreader/wiki/Installation-on-Kobo-devices

Koreader is available from the Play store if you have an android phone, you can try it out first. Its very customisable, I spend hours tweaking the settings because that’s my idea of fun 😂