Get a broken 27" iMac, rip out the guts, and slap in a converter board that adds a bunch of inputs. It's not nearly as difficult to build as most of the blogs make it out to be.
Mine's not even broken, but it is corp, so sticking an Aliexpress board in there is ill-advised. Hence, in the market for a 5k when I've had a perfectly good one on my desk since 2017.