@Joannes They aren't unique, but we have a plan! The @ chooser needs to work well enough that you can efficiently choose the right person. From there, we can know a unique ID.
What about supporting Namecoin name registrations? e.g. id/memouser resolves to an address associated with memo account. Private Key is the same on BCH and Namecoin.
Memo backend can handle both BCH and Namecoin transaction (very similar networks). If Namecioin Identity is found for a particular Memo public key, the UI displays and highlights it.
Namecoin registrations are very cheep, 0.01nmc or ~6 cents at current prices. FYI, Namecoin is the first ever fork of Bitcoin, and Satoshi participated in it’s discussions.
Also, Memo can have special “associate domain name” action, and if this domain has “memo”:”%account address%” in its TXT DNS record, the UI displays domain name in profile
If Roger has performed “associate domain name” action and put rogerver.com in opreturn, memo backend fetches dns record, verifies it, and if ok UI dispolays green mark next to name