"Mechanical keyboard" as a description always confuses me, because the line people use seems so arbitrary?
Like sure a touch virtual keyboard isn't mechanical in any reasonable sense but it's not like rubber dome, scissor, or butterfly switches aren't based on mechanical parts, and in the other direction optical and hall sensor switches count as "mechanical" but are definitely less so than most of the other ones mentioned
Personally I'm inclined towards "if your key presses involve physically depressing some kind of button, no matter the exact mechanism, with a keycap on top, that's mechanical enough to count"
But mostly people just seem to use it for "separate keyboard that I bought because I didn't like the one that came with the device" and emphasizing the "mechanical" there just seems weird