[Dylan16807]

Are there DIY Arm boards that make a good HTPC? Do they have hardware video decoding?

[ihsw]

Your best bet is going to be Raspberry Pi devices:

https://github.com/blakeblackshear/frigate/discussions/18431

You can try Googling around for bespoke products but they will almost exclusively come from China and they will be very overpriced due to the soldered RAM.