This appears like the biggest problem the Open AI API standard supported by all the tools doesn't include support. I've not used routstr, etc to see how they work but I assume the user would need to run a local proxy to inject the tokens and collect the change.
Discussion
Would this be a big deal? I'm not sure. The service could run their own custodial proxy to onboard new users with the account based experience nostr:nprofile1qqsdy27dk8f9qk7qvrm94pkdtus9xtk970jpcp4w48k6cw0khfm06mspp4mhxue69uhkummn9ekx7mqpz9mhxue69uhkummnw3e82cfwvdhk6qg5waehxw309aex2mrp0yhxgctdw4eju6t09x35fm do today.