I could have stopped with a Microsoft Natural keyboard and been fine pain-wise, but I had already started down the mechanical rabbit hole and missed the feeling of mechanical switches. The basic ideas of split, tenting, and reverse tilt helped a ton, but I could have been fine without column stagger or a reduced layout.

I now use a 40-key low profile column staggered split with Colemak-DH and it’s a joy to type on. Learning Colemak-DH was probably the lowest benefit to effort of all the changes I’ve made, so I don’t exactly recommend it. Now that I’ve already spent the time to learn it, though, it’s definitely comfy to type on. If you want a mobile setup though, I think a split board like a Corne, Sweep, or Totem, or one of the many derivatives would be a great upgrade for your tablet setup. There are a few solutions for tenting but you may find you don’t need it - while it was essential for me at first I’m now fine using a split board flat on the desk.

I also found a vertical mouse made a big difference- I used the $15 one from Anker for a few years. Trackballs can be good too. I also noticed holding my phone put my wrist at an awkward angle, so I got a pop socket and that was helpful too.