For Drive and Photos, Relica can do this. Full disclosure: I develop the software.

It uses restic under the hood (so you get deduplication, encryption, immutable snapshots) and rclone for cloud connectivity. Backs up to your NAS or multiple destinations, runs on a schedule, GUI instead of cron jobs and scripts. $5/month for the software, storage is yours.

Gmail is harder. It's not a filesystem so restic/rclone-based tools don't handle it. Your best bet there is probably Google Takeout on a schedule (annoying but works), or something like gmvault if you're comfortable with Python scripts.

The lockout fear is real. One option: backup Google Drive → your NAS → a second cloud provider that isn't Google (Or Relica Cloud for managed redundancy). Relica can chain those so you upload once and it replicates. Check relicabackup.com