I'm very good with electronics (repairs and care). I'm on an unlocked Note 20 ultra I bought used in early 2021 and it's still in flawless condition. Not parting with it anytime soon and already replaced the battery in it so it would keep going.
Issue with things like mint or rocket is that you get bumped down in priority as soon as towers get a bit congested. I'm paying more, but I like having unlimited data and 40 or 50 GB of hotspot a month.