Not hard to set up, using docker compose. Just remember to set up automated backups, since there is no company taking care of that.
you get $5 in credit without entering a CC
"The project is under very active development. Expect bugs and changes. Do not use it as the only way to store your photos and videos!"
Combining it with "The Search Page" app makes it a quite comfortable experience as is.
Other than that it's just installing a Nextcloud app and pluging in a URL and API key
Now, if you worry about some use you wouldn’t like… These are declared in open, if possibly too large, text in all the privacy policies. As a Googler I can tell you the internal bureaucracy for upholding these is dead serious. My product is used only by Google employees in their work duties, yet it took a couple months for us to get access to stats of our own UI. Something like an ads subsystem wanting to read a photos data field is likely to involve quarters of disputes with multiple lawyers.