...it should be fine as the security at the gates/wall were checking bags, not tickets - I didn't show my tickets at the gate/wall for either of the test events, just at the actual turnstile.

I don't know for sure if that will be the case when it's full capacity, but I'd suggest it will be the same as otherwise that's a big bottleneck with just those 4/5 gaps in the wall to check 52,000+ tickets.

If you think of Goodison, there is no restriction on who can access the Fan Zone on matchdays, however it's locked on non-matchdays - I suspect that will probably be the same at BMD.