You could, and this was before banks and such blocked your device if it was rooted. Still wasn’t accessible to most, and if you had a carrier variant you were probably out of luck.
ive had 2 old touchwhiz phones, i often replace the home screen of my phone and on one of them, event the notification shade. On the old s5, featues didnt mesh well and on both the notification shade was an awful unchangable theme. I once made a touchwhiz phone un-factory-resettable
Im on the pixel 7 purly cos of size. Graphene has been great turning mic and camera on and off can get a little tediouse but u dont have to use that feature if u dont wanna bother. Accessing the same file from different apps can be a little anoying sometimes due to sandboxing but nothing too seriouse. Took me a while to set things up how i wanted custom launcher, keyboard, fdroid etc but im very happy now no issues at all, ive heard people saying some apps like bank apps etc dont work i have never encountered this issue google servuces conpat works perfecrly. Well except for android auto but a recent update suposidly fixed that i havnt tested yet. Its development seems very active u can get a rundown of updates as they come out here !grapheneos@lemmy.ml . Im never going back to a proprietery os without the security features graphene offers ever. U might wanna check out the alternatives tho ive heard good things about LineageOS as well. Only thing u might wanna watch out for with graphene is the dev/s have mad beef with practicaly everyone.