SimpleX could use Nostr for discovery, but it requires support from clients first. It would be very easy to add a field for SimpleX addresses, as was made in this proposal: 
Once this is added, SimpleX could add in-app support for discovery via Nostr, similar to how many Lightning wallets already do it.
GitHub
[FEATURE] SimpleX Chat links in profile · Issue #8 · retrnull/garnet
Is your feature request related to a problem? Please describe. Nostr DMs are unsafe. Developers keep churning out new flawed DM systems and nobody ...
