Committer here. I would love to hear more about this scenario.
Is the proposal to be able to export pg_dump formatted data on some schedule or trigger, entirely hosted in PostgreSQL and with timeouts? There are already extension that can export to blob/file storage and can be combined with pg_durable or pg_cron, so I assume the challenge is pg_dump compatible data export from SQL running in the database?
One would be able to trigger maintenance jobs via simple lambda functions whose duration is capped.