Okay, I feel like I have a better idea of what you’re looking for now.
Unless you’re using some sort of shingled drive, reads from the magnetic platter should be non-destructive, so reading files for seeding shouldn’t do much to the drives in terms of wear and tear.
External drives are fine for durability, and if you get them from a reputable company I’m sure you’ll be happy with them. Buying cheap, high capacity external drives and shucking them is a common tactic that some data hoarders will use to get the most bang for their buck. Remember that external HDDs are going to be subject to more stresses than a normal drive (people moving them while they’re on, etc), so it wouldn’t be in the best interest of the manufacturer to make them less durable than regular HDDs. You just have to keep in mind that HDDs are mechanical in nature. Anything with moving parts will wear down over time and eventually break. Typically you should expect to cycle through your drives every 4 years or so (I say this while never having cycled any of my drives and they are all working fine).
I see you also keep picking drives that have NAS in the name, just so you know, that’s mostly marketing bullshit. They name the drives with different use cases so they can charge more for them and get that little bit of extra profit. There’s very little that can be done to tune the drives firmware for those different use cases. So, just get the most capacity your can afford from the company you want to use, and don’t worry about it it has NAS in the name.
You’re going to want more storage capacity, so don’t lock yourself down with a tiny case like the Node 304. Get a case that can hold a lot of HDDs. I went with the Node 804, which has mounting spots for 8 HDDs and two 2.5" SSDs (more spots than that when you realize that SSDs have no moving parts, so it doesn’t matter where you put them). I ended buying a new bigger case within a year of building my NAS, so definitely leave yourself room to grow, it may cost more up front, but will save you money in the long term.
As far as the GPU goes, I initially got a Ryzen 3400G, which is an APU, so I just used the integrated graphics. Since then, (remember how I bought a new case within a year?) I have upgraded the CPU to a Ryzen 3800x without onboard graphics, and I am now using this motherboard, which has onboard graphics, as well as IPMI. The IPMI is amazing, and I highly recommend it; it’s allowed me to have the computer in a remote location far away from any monitors, and it only has Ethernet cables and a power cable connected.
As far as other options goes, you could also get a bigger case for the computer you already have, that would allow you to add more storage. You could also get a very large SATA SSD (I just saw an 8tb one for ~$340), and you could just shove that into your current case anywhere to hold you over until you save up to get a more dedicated build going.