As you know they have dropped the ball with legit shiny Solgaleo/Lunala. The fix is pretty easy if you have a shiny Cosmog. See if you evolve Cosmog on Sword and Shield it registers it as a legitimate mon and you can do online shiz. You're welcome... Still working on necro boi... will get back to you.
(first post and i hope it helps)
Cosmog for your convenience