Starting over and doing it "right"

Y'all, this is gonna be super broad, and I apologize for that, but I'm pretty new to all this and am looking for advice and guidance because I'm pretty overwhelmed at the moment. Any help is very, very appreciated.

For the last ~3 years, I've been running a basic home server on an old computer. Right now, it is hosting HomeAssistant, Frigate NVR, their various dependencies, and other things I use (such as zigbee2mqtt, zwave-js-ui, node-red, mosquitto, vscode, etc).

This old server has been my "learning playground" for the last few years, as it was my very first home server and my first foray into linux. That said, it's obviously got some shortcomings in terms of basic setup (it's probably not secure, it's definitely messy, some things don't work as I'd like, etc). It's currently on its way out (the motherboard is slowly kicking the bucket on me), so it's time to replace it, and I kind of what to start over (not completely - I've hundreds of automations in home assistant and node-red, for instance, that I don't want to have to completely re-write, so I intend to export/import those as needed) and do it "right" this time - at this point, I think this is where I'm hung up, paralyzed by a fear of doing it "wrong" and winding up with an inefficient, insecure mess.

The new server, I want to be much more robust in terms of capability, and I have a handful of things I'd really love to do: pi-hole (though I need to buy a new router for this, so that has to come later on unless it'd save a bunch of headache doing it from the get-go), NAS, media server (plex/jellyfin), *arr stuff, as well as plenty of new things I'd love to self-host like Trilium notes, Tandoor or Mealie, Grocy, backups of local PCs/phones/etc (nextcloud?)... obviously this part is impossible to completely cover, but I suspect the hardware (list below) should be capable?

I would love to put all my security cameras on their own subnet or vlan or something to keep them more secure.

I need everything to be fully but securely accessible from outside the network. I've recently set up nginx for this on my current server and it works well, though I probably didn't do it 100% "right." Is something like Tailscale something I should look to use in conjuction with that? In place of? Not at all?

I've also looked at something like Authelia for SSO, which would probably be convenient but also probably isn't entirely necessary.

Currently considering Proxmox, but then again, TrueNAS would be helpful for the storage aspect of all this. Can/should you run TrueNAS inside Proxmox? Should I be looking elsewhere entirely?

Here's the hardware for the recently-retired gaming PC I'll be using:
https://pcpartpicker.com/list/chV3jH
Also various SSDs and HDDs.

I'm in this weird place where I don't have too much room to play around because I want to get all my home automation and security stuff back up as quickly as possible, but I don't want to screw this all up.

Again, any help/advice/input at all is super, super appreciated.