Looks like I can get a Shimano SC-M9050 Di2 XTR display on Amazon for $80. Is there only one display unit available?

I have not looked into progamming the shift switches. My "muscle memory" from mechanical shifters tells my brain that the forward switch moves to a larger cog & the rearward switch moves to a smaller cog. Though this seems less than intuitive, that is dictated by how mechanical shifters work.

Have others found some other arrangement better? Is this a little like using a QWERTY keyboard on a smartphone? If I select some other arrangement, will I have trouble switching back & forth between Di2 & a bike with mechanical shifters?