The best solution in my opinion is to buy 5y old, used, server motherboards and CPUs (like AMD Epyc 3 right now). They are fairly cheap, it is durable products designed to work 24/7, and it comes with a huge number of PCIe lanes and extensibility. Same with enterprise SSDs for home usage, which is usually very little write. A used enterprise SSDs with a ton of endurance and very little writes is probably the best bang for your bucks. Wouldn't do that with hard drives though.
Yeah, I assume most home users these days are never pushing a NAS beyond 1Gbe, and 99% of people who have faster networks are still probably just doing 2.5Gbe (still just talking about home use). This wouldn’t make that PCIe bandwidth sweat.
