All of them? As long as eventually the connection is restored and the transaction can propagate over the network.

The point of the ledger is to prevent double-spending.

Offline payment specifically allows double-spending. If you have offline payment, you don't need a ledger at all; you can just use PGP.

Those transactions simply won't be accepted. Sucks for the seller, but how to deal with that mess is an issue that has to be solved on an upper layer by ToS or laws.

Also, "all of them"-- as in, when you pay multiple parties offline with the same exact crypto-dollar, all of them will get paid.

Even better, when you're back online the network will run a sanity check to protect against the evils of inflation.

(Note: inflation-check fees will vary between 0 and 100% per payee.)

Doesn't Solana require the hash of a recent (~ 1 minute) block before signing?

They do, but the payee accepts risk.