Basically we intend for it to work eventually on android, but it didn't get prioritized.
Stylo can be disabled at build time, and this was the case for 55 and is still the case for android. We don't remove the associated prefs in that case (about:config doesn't have UX because it's not exactly user facing).
You can go to about:support to see if stylo is actually enabled. There's a "stylo" column. It's not there in 55, but no 55 release has stylo enabled at build time; so if you don't have that column at all, stylo isn't there.