In the case of silent payments, however, you don't share your xpub at all, replacing it with a deterministically derived silent payment address, which is basically a hash of a public key (not a master public key) encoded in a special format. In the latest implementation, it was proposed that silent payment addresses should start with the "sp1" prefix.
I know; just wanted to point out that xpub sharing (as
alternative to silent payments) is not only less private but also potentially insecure.
Where can I find more information about the
latest implementation or proposal? I'm interested to see what the creators think / how they handle SPV wallets and the complexity / burden of scanning for transactions.
Yes, this is exactly what sprung to mind when I read this proposal. In my opinion, the biggest disadvantage - just as in Monero - is the need for transaction scanning.