So, after I faced the squeeze from a reasonably wide 3-bet range, I didn't really know what to do. I didn't want to call as I then would have to go 3-way to the flop, and I didn't want to 4-bet fold. But I went with the latter in order to push out the BTN and push my equity against SB. His range does have a ton of equity against me still, but felt like the best option.

Then comes the flop. SPR under 2. He isn't too likely to have a 4 but he has some. I consider betting something like 30% pot, but that prices in all of A23ds, A25ds etc. I don't think he has AA as he didn't 5-bet pre. So I opt to POT to push out the mentioned hands.

Thoughts on the hand? Things I should/could have done differently?

Pretty easy flop pot once you 4bet.
Also he has a hand that should really not flat the 4bet pre.

I think flatting pre is fine, though your idea might be just better at this depth. Flop obv bet-getin, no need to worry about sizing as you are just bet-getinin 100% of your range. Kudos to villain for making a play at .1/.25 that like 5% of the players at 1/2 or 2/4 would be able to make.

Although I don' t really see this as a squeeze from a wide 3bet range, I think you played it fine. Flatting 3bet seems fine too. You are blocking AA so 4bet has some merit. But I like how villain played it, knowing your range is weighted towards high pairs.