For those kind of issues I’d recommend snapshots instead of backups

With the very limited number of drives one may use at home, just get the cheapest ones (*), use RAID and assume some drive may fail.

(*) whose performances meet your needs and from reputable enough sources

You can look at the backblaze stats if you like stats, but if you have ten drives 3% failure rate is exactly the same as 1% or .5% (they all just mean “use RAID and assume some drive may fail”).

Also, IDK how good a reliabiliy predictor the manufacturer would be (as in every sector, reliabiliy varies from model to model), plus you would basically go by price even if you need a quantity of drives so great that stats make sense on them (wouldn’t backblaze use 100% one manufacturer otherwise?)

In your shoes, I’d put the money in a proper case (eg. fractal node 304/804) rather than an USB enclosure (no, you don’t need hot-swap for a home server): besides the performance issues of USB (which may or may not be an actual issue depending on what you plan to do with the NAS), having a single box makes everything simpler.

For components to fill up the case, you can look at second-hand computers on ebay.

As for the OS, if you are not familiar with linux you may want to look at truenas scale (which is linux).

If you never built a PC, you’ll have to do a lot of research not to buy incompatible components… otherwise you could rely on a friend/shop or stick to sinology and similar.