Is it safe to assume that payments to federated stellar addresses username*domain.ltd are universally supported?
Are there wallets/apps out there that would possibly reject those? Because they have some properiatary input validations that look for an account id with 56 alphanumeric characters for example.
Should my app have a fallback that displays the account id instead of the federated stellar address optionally?
Federation support is reccomended by SDF (see SEP-0002), but not mandatory.
Some clients do not support federation addresses, for example, exchanges like Bittrex or Poloniex. So it would be better if you provide an account address alongside with the federated address. Make it smaller or semi-opaque, but give your users a choice to use both.
For as long as the Federation server is up, it will relay the information to the Stellar public address.
However, from the developer page, it states that the Federation Requests types of id and txid are not technically supported by all federation servers, so you have to take that into account.
