It looks like it could be fun, but I am confused on the hit points for the shield, do they add their CON modifier to the temp pool as well? So if they move 1 die over, they also get their con top of it as well?
A rogue with it would be insane because of being able to hide very quickly, so they go out, get hit and then bonus action hide and regenerate a high amount every round.
I think the regeneration part might make it OP, maybe instead of all of it make it regenerate the proficiency modifier plus the amount of hit dice assigned to the shield. Meaning, if they invest more into it, it will regenerate faster as well. The cover is nice, but I think it could make it more confusing as well.
I hope that might help a little bit, have a slice of !PIZZA for the idea! :)