Perhaps a bit harder (?) on the 2015 MBP since you need an adapter and an OS update.
Probably a wash as there's no thermal paste situation to deal with on the 2015 MBP
All of it -- on Surface or 2015 MBP -- is well within the realm of any moderately experienced PC user/builder/enthusiast though.
That's all I've wanted from ASi options -- just the ability to do it.
I don't want or need Apple to support or encourage it ... or advertise it!
I just would like it to be possible to swap in my own NVMe storage upgrade (RAM would also be nice, but NVMe is easier to support)
So much would be solved on ASi for me with 16GB RAM base across the board and slotted NVMe
Suddenly a wide world of preowned Macs are open as options