Thanks. Thinking about it some more, the main use case can be solved with just receiving — so exporting the xpub to integrate it as a watch-only wallet in BTCPay works fine. More here nostr:nevent1qqszwf5n54lxlf73j9qu9crg7mh84gpzpy8y9unjarc4rl4a4t7lkqcfcxhd4