This macro adds selected photo(s) to an album chosen from a list of existing albums. Obviously, it doesn't work with smart albums, so I had to find a way to strip out the smart albums from the picklist of albums. (You don't have to do that if you don't want to.) I could not find a way to make this work well without adding "(Smart Album)" to the title of each of my smart albums. It's just easier to strip out the smart albums that way given the variety of names and words in the titles of the smart albums. You can delete the applicable actions if you like, however.
ADD TO ALBUM.kmmacros (55.4 KB)
I cobbled together the Applescripts from these two links, whose content authors are to be credited with making the sausage:
macOS Photos and AppleScript: Quicker organization method - Stack Overflow