I still think the best bang for your buck is an old desktop PC. Something like an i5 with 8GB RAM and an SSD will suit 99% of home server uses with capacity to spare.
Even in this environment of inflated hardware prices, you can get one for a reasonable price.
Although I do see the appeal in getting unconventional hardware to do what you want, just for the love of the game.
I just bought a refurbished Lenovo k14 with 32gb of ram and Corei7-1165G7 with 500gb for 350$ which I'll use as my 2nd home server.
My first home server is a 2nd hand gaming PC that I bought for 500$ with 32gb and 7700rx video card that I use for GPU based tasks but it's quite audible when it's working so wife and I agreed it has no place in the living room anymore and is being deported to the corner of my office.
You can still find really good bargains for home servers from refurbished good computers, and given how well solved tech reliability is now, it's really not worth buying new.
This is my situation exactly. Got an i5-4570 with 16GB, no GPU, running Unraid with a bunch of containers for Jellyfin, qBittorrent, Crafty Controller (minecraft), HomeAssistant, etc.
I'm using a PCIe expansion card to get double NVMe drives for the cache disk, and then three (up to five) 3.5" spinning 8TB drives for long term.
I tried really hard to get it on 32GB but sadly the motherboard only has two slots and only supports 8GB DDR3 modules. I literally ordered some of the rare late-generation 16GB ones and it refused to boot, with no firmware updates available from the vendor (Advantech, board is an AIMB-274).
Yep. My 2010 server does everything I need incredibly well, and I see no point in retiring it anytime soon.
ASRock H67M-ITX, i3 2.5GHz, 16GB DDR3 1333Mhz, 2TB+4TB SSDs, DVD-RW, in this Mini-ITX Antec case[1].
It only makes sense if we are measuring raw capability per dollar. Once you factor in noise, physical size, idle power, battery etc, I think the calculation changes.
For a home sever that's mostly idle, it is almost like commuting in a pickup truck.