While the technology you are developing may allow that proof of COVID status, as the OP mentions, it is questionable if it will actually be used broadly in many countries. When countries have already reopened their hospitality sectors to all regardless of status, then they may be loathe to begin requiring COVID proof. Nor do hospitality staff necessarily want to given the duty of checking statuses.

So if COVID status proof is required country-internally over the coming months, in many countries it will probably be used for mass events (e.g. the UNTOLD festival in Romania) but otherwise not.