Just pirate it. Minecraft is really easy to pirate if you don't want to play multiplayer, or want to play on pirate-compatible servers (which is one boolean flag in the official server configuration file and doesn't require a pirated server).
Make sure to get Java Edition. The other one is just an ad-riddden slopfest where they also ban you if you say swear words.
That is my plan, I have (had, you have to let it go) an old account from when it was a just username, never bothered "updating" it to the email account, I tried to convert when Microsoft said they were dumping all the old accounts, but the process was not working and I quickly decided I don't actually want a Microsoft account. At which point I decided that if I ever wanted to play again I would just do so sans account.
Which raises an interesting question, If I legally have a license for the game but they shut off the license servers, is it actually copyright infringement? (or piracy as people like to call it because copyright infringement sounds lame)
It isn't if you can afford enough lawyers to make microsoft's legal department blink at the cost of prosecution. If you can't drop $10K+ on a lawyer at the start though I would not put any money on winning.
They will certainly argue, and win, by saying that for legal mumbo jumbo reasons, you only have permission to play it in the exact ways they say you can, and if you already bought the game, but they say you can't play, then it's illegal to play.
Which is why coming at this from a legal perspective a farce. Most of the world is like this, actually. You can assume that if some action brings money to large corporations then it's legal and if it takes away their actual or potential revenue then it's illegal. Go with what you feel is morally correct.
The point of the account was multiplayer, unfortunately. Wanted a locked down account to play the game with a closed group of friends.
Ended up on Minecraft Education on the computer, eventually.
Closed group of friends works fine in offline mode (pirate friendly mode).
If you can get a group of other parents to also pirate...
Not really in the cards, though I can appreciate your dedication to pirate advocacy.
The referenced config setting is apparently literally just whether to have the server authenticate accounts with Microsoft, so pirate and nonpirate players can play together on a server with checking off.