A lot of people saying ditch the Pi, but it’s fairly viable depending on what exactly you want from it, so long as you get one of the newer models with plenty of RAM. Simply streaming media is relatively manageable for a Pi. It will most likely run Navidrome okay, and Jellyfin will be okay if and only if media doesn’t need to be transcoded, and you MIGHT have issues with 4K, not sure. If you stream to something like a smart TV or Fire Stick, those can typically only handle certain video formats, so if your media isn’t that type, either the server transcodes it, which the probably Pi can’t do fast enough, or playback fails. Music typically doesn’t require transcoding, so that’s why I think Navidrome should be okay. Pi-Hole is manageable and is, after all, expressly designed to be run on a Pi. It can also be run on standard hardware, so while you can do it on a Pi, you don’t need one to use Pi-Hole.

Now, that said, two main concerns about a Pi. The first is that you’ll probably eventually want to host and do more, and you may run out of resources and wish you’d just gotten a cheap mini PC instead. The second is that you really should get an external HDD or something to store as much as you can on, preferably including the OS. An SD card just is not meant to handle the constant I/O that comes with being the main drive for a full computer. It’ll eventually fail, taking all the data on it with it. I think the best way to run off an external HDD has changed since I used a Pi, so some research recommended, but what I did before was flash the EXACT SAME image to the SD card and HDD, then delete the boot partition on the HDD, expand the data partition to fill the HDD, and delete the data partition off the SD card. If you use the exact same image for both, it at least used to be that the partitions keep the same UUID, so it boots from the SD card as normal, and when told to find the other partition by UUID, it finds it on the other drive and works just fine.