I moved to Zillium (Zoho Family plan) but not 100% happy with them. Heaps of threads on migration and options on the Google Workspace Reddit starting around the time they tried to remove the free legacy plans.

Would probably get more zanier responses on the Home Automation or Home Assistant subreddits.

Synology Drive is rock solid. Not open source though if that’s important to you and technically requires Synology hardware.