hmm, if it's an x86 chromebook i'm assuming you could install linux on it like any other x86 device... not sure tbh, i've never done this π
if it's ARM, then postmarketos may be your best bet, it's typically used for phones but they have many laptops supported as well. maybe yours would work!
i've seen stuff like crouton, chrx and galliumOS which are all projects that are supposed to help run linux on chromebooks, but they're all abandoned as of now so i wouldn't recommend them.