It appears that the birthday commemorative posts for the upcoming year is going to be cheki polaroids, yes, and the cycle always begins with cozmez for logistics reasons*.
The fact that they are specifically cheki plays into the "characters as in-universe performers" thing that they're going for a lot harder with BoU, what with the characters doing photoshoots for album covers etc.
(And, idk, man, people were mad that they did mini-dramas last year instead of getting new art, so, www, you can't win em all.)

(*They had the first birthday in December 2019, after Paralive was first announced in November 2019, and so they're first up in the birthday rotation; any birthdays between the anniversary and December 24th were later additions, and so didn't get put into the rotation until a year had passed.)