Late to the party, but I’ve read that OP is going to be the sole admin. Do Not Do This. I admire what you are trying to do, but ultimately, you will have no rest, no vacation, no backup for yourself. The hardware & software aren’t the issue here - it is the human support of those services. You will put a single point of failure on yourself, and likewise your peers.

Many of the FOSS projects you mentioned have commercial services. SAAS exists for a reason. By subscribing to those services as a business, you underwrite their ability to provide the software for free to the community. It’s a win-win.

I just use SMB shares on my NAS. Why over think it?