DecentM

The cutscene was hardcoded it turns out

No matter how many times I watch Flow, it never fails to make me cry by the end.

Depending on your specs, I don’t think you need to buy hardware. You can scale later if you run out of resources. This is how I’d separate your stuff:

• Desktop: SteamOS (or Bazzite IMO), for gaming. Install Kodi on it for the HTPC interface, and add a shortcut to it on the big picture UI
• RPi: Home Assistant OS. They have images for the Pi, which will let you install updates and addons from the gui. Addons are just containers, so you may be able to run a service or two if you run out of resources on the other machines.
• Compute stick: Some server OS (I personally like Fedora Server, but loads of options are available here. Bazzite is Fedora based, so you can use knowledge you gain on one, on the other). Nextcloud (reconsider this, Nextcloud is a complaint magnet from what I can well, there are alternatives to most of its functions), your *arrs, torrent client etc. Stuff that is okay if it goes down for a bit.
• Laptop: Same OS as the compute stick. Whatever doesn’t fit the stick, plus Pihole/Adguard. For DNS though, I’d recommend using a cloud provider instead of self hosted, because if it goes down, you’ll be stuck reconfiguring your DNS before fixing it (since if dns goes down, you can’t easily access websites to look up stuff). IMO NextDNS is a good option, both free and paid tiers, and it does adblock lists too.

Edit:

• For remote management, ZeroTier and Tailscale are both good options at the moment. I use Tailscale, but they recently announced they want to IPO at some point, so I’ll be moving to Headscale (the self hosted version essentially) if they start enshittifying.
• For remote gaming, check if Steam remote play works, or set up a Sunshine server on your PC.