Self-Hosted Main

The NAS can do almost everything you need except offsite C2.
For example Synology ((so far I only had these)) has a built-in DynDNS service that gives you a subdomain you can access the NAS through without extra steps. I bet all the other NAS brands have this built-in as well. Whichever you pick, definitely have 2FA enabled. Also if you can setup your storage pool as btrfs that's great too.

As others pointed out, you need an offsite copy on some C2 provider or a friend's NAS or whatever. (if you've really no budget, you could get a bunch on free subscriptions (dropbox etc.) and split up the backups between them).
The NAS will have an app that already supports a whole lot of providers + things like external USB drive and you can setup automatic backup there.

Plex has the "luxury" of auto-configuring my router and somehow mapping its IP so I can "just connect" from everywhere.

Let's be reasonable. If you're going to be away from home I'm sure you don't need all of your content "at a moments notice".

If you do you wherever you are that's you're new home!

In this instance my advice would be to get a small SBC or RasPi + some external storage which you could load up + rotate your content when you travel.

For me I'd add a "travel router" which provides:

• Expansion of number of devices that can access the internet(hotels)
• Minimization of security + privacy configs across devices as it can be setup on one - the router
• Access to SBC/Raspi(and my content) on the LAN

You didn't say why you wanted to remove your data from the cloud (leaving Google is a very good reason though) but I wanted to offer another perspective. I don't like opening up my homefirewall for anything so I have a VPS to host my data in the cloud. It gives me control while still allowing access to my data from anywhere. Kind of a halfway point between self hosting and using public cloud services.

DynDNS with wireguard if you can port forward or tailscale if you can't or are behind CGNAT.

Synology NAS + Tailscale