I just recently got myself a Pi 4 8GB for €86 on Amazon, a barely used 10TB IronWolf NAS HDD for €120 on eBay, and an HDD enclosure for €20 that powers the HDD and plugs into the Pi via USB3. Currently it’s running Plex Media Server, qBittorrent, Wireguard, AdGuard Home, Nextcloud, Caddy, and a few monitoring containers. It’s handling all of that easily. I’m using it headless and just stream content to my TV. Currently I have no redundancy for my drive, but I’ll get around to that eventually.
You can of course keep using PiHole for your setup. I recommend you check out !selfhosted and r/selfhosted.
You don’t even need to buy a microsd card anymore because they now ship with the firmware that can boot from USB.