You can run Google Play services on GrapheneOS it’s called Sanboxed Google Play. It allows you to run Play services as a normal app without any special privileges so you can install it without sacrificing all of your phones data to google. Should allow you to use pretty much all Google apps.
As far as I know there aren’t any tools to do that, Lemmy doesn’t automatically fetch older / deleted posts from federated communities like that, the reason is the way that federation works. When a user subscribes to a community on another server, that server will then start notifying their server when there’s new posts, comments, etc to fetch, but Lemmy doesn’t fetch older content, so only new stuff from that community will show up. I believe it’s possible to fetch old posts and comments using the search function though, you can read a bit more about it here: Lemmy docs
My instance is just me rn but I’m federating with about 500 communities, including all of the most active ones and Lemmy is running really well. My system is only using about 10% cpu and about a 1gb of ram, I’m just using a Hetzner arm vps with 4 vcpus and 8 gb of ram. Even a single small server should be able to handle a lot of users imo.
piped.video is the same instance as piped.kavin.rocks