On Android 12+, how do I disable mobile internet without disabling MMS?

My good old phone from 2013 is dying. I have been satisfied with it, but even if it was still sold nowadays, I would not buy more of the same since it’s becoming increasingly difficult to not have either an iOS or an Android phone. I don’t want iOS for reasons not pertaining to my question, so Android remains, however, constant internet access is blocking me. There are a few reasons to disable mobile internet on one’s phone, but I’m not here to discuss these. I just want to be able to disable mobile internet. There are tons of sites giving tutorials on how to do this, but as far as I’ve seen, none gives a correct reply, because : 1. Either they provide steps on how to disable mobile data, which indeed disables mobile internet, but MMS too in the process 2. Or give a per-app solution, which won’t really completely block all mobile internet traffic, let’s be honest A few years ago, someone with a Huawei phone asked me for help on this very subject, and I was indeed able to help him, by defining explicitly which APN was for what, keeping only the MMS role for the MMS-only APN and removing everything else. And it worked. But things may have changed, and I certainly don’t want to buy a phone only to find it’s now impossible. If it’s become impossible indeed, then well, despite the drawbacks I will definitely get an oldie. **So, more concisely :** - How can I disable mobile internet ? - Not per-app, system-wide - MMS shall remain enabled - Android 12+ (I suppose that’s what all new phones are running nowadays) - I’m not afraid of using adb and going through a shell - No third party programs - Jailbreaking/rooting is a big no no, if I have to fight against the phone vendor, then I better buy somewhere else - Which brands leave it possible ? - Which brands block it ?