A single node command that would simulate/test minting blocks with pools stake and keys and a return that can be reported or verified to pool explorer sites. That would unequivocally confirm that the pool’s BP node is capable of minting blocks.
Currently there are many indicators and checks of various technical difficulty SPO is required to do (pool registration) or can additionally do (key checks against ledger state) but even with all of them SPO is not sure everything is in order until a block is minted.
The biggest issue is that small SPO can wait for several months until they are finally selected during which they or their delegates might leave the pool or owner to leave the network.
If possible to create such a feature it would be extremely helpful to small SPOs now and in future.