Fujitsu Esprimo here… 50 €, before the extra RAM, SSDs, … Relatively low power usage, lots of SATA, PCI slots, lots of USB ports… Works very well for all except transcoding. Could put a GPU but it would really make power consumption go up

Why not a second hand small “business” or office pc? There are so many on the market now because businesses are replacing because of windows 11, while the hardware runs perfectly fine with Linux for probably many years to come. Buying one of those is cheap and reduces e-waste.