This is the substantive blocker for (easily) using gmailr with a service account (another incidental obstacle has just been removed in #186, which was the unconditional requirement for an OAuth client). Indeed the previous issue #160 has some messages that are very relevant to this new issue, specifically: https://github.com/r-lib/gmailr/issues/160#issuecomment-1252929589.
This is the substantive blocker for (easily) using gmailr with a service account (another incidental obstacle has just been removed in #186, which was the unconditional requirement for an OAuth client). Indeed the previous issue #160 has some messages that are very relevant to this new issue, specifically: https://github.com/r-lib/gmailr/issues/160#issuecomment-1252929589.