Convert 24 Coop DRT to 12spd Deore

Hey there! My 7yo son has a 24" DRT Coop bike (linked below) and he is riding 20-30mi a week on trails. While 8 is great, I think he could benefit from some more – but I am coming from a road bike. Realistically I think he has 3-4 more years on this bike size wise. I was wondering if I could upgrade from the Shimano Tourney Revo 8-speed to something like the 12spd M6100 deore I have linked below. If I can, is it worth it to put the 4 piston Shimano M6100 groupset on? Or is 2 piston fine?

Co-op Cycles REV DRT 24 Kids' Mountain Bike | REI Co-op

Shimano Deore M6100 Mountain Bike Groupset (Black) (1 x 12 Speed) – Performance Bicycle (performancebike.com)

Im still learning the compatibility side of things, but recently rebuilt the bike at his moms house with new hydraulic disk brakes, new derailleur, etc. and own quite a bit of cycling tools from my road bikes. So mechanically I think I can handle this.

Thank you!