This is a car crash, please stop.
We have an op who clearly has absolutely no idea what they are doing and why with a bunch of people, who should really know better recommending what works for them and that dinosaurs should be re-introduced, I feel like I have read/seen this somewhere before, it never ended well and produced some awful sequels.
Op, if you want to run a NAS/home server then that's great, it's a learning experience that can set people off in unintended paths as you'll gradually realise you can do all sorts with the right box, but this is really not the way to go about it. You mention TruNAS because seemingly you've heard of that, TruNAS is one of many distro's that exist, it's a decent choice in the right circumstances, but it's made a development choice that has very specific advantages and as a result a price has to be paid. What does your likely IO usage look like? Heavy sustained R/W or Write Once Read Often (WORO)? If it's the latter and on the assumption you don't have a bunch of matched drives kicking about but instead but whatever was the best £/TB at the time, have you considered UnRAID and it's pool/parity approach? It also has trade-offs in terms of R/W speed, but it's easily expandable and tends to favour people who want a NAS that runs services.
In hardware terms, for a reasons I don't fully understand you often find people who get the idea to build a 'server' suddenly think they need to buy some ancient ex-corp box because it has xyz. They rarely - if ever - do. Don't buy someone else's e-waste, the term Xeon covers a lot of chips, they range from something that is almost identical to the equivalent generation of desktop chips to high core/power server/workstation CPU's that drop things like iGPU and have more PCIe lanes than most people know what to do with. The thing is those chips are designed to run in well cooled DC's and the hardware is often not flexible or designed for home use. Hot, noisy, fans at 100% if you install an uncertified card, no BIOS updates unless you have a support contract etc. It needs some time spent working out what you need. The elephant in the room is Ryzen, it was the global extinction event to Xeon in this market. Xeon was capable of decent performance, but Ryzen was capable of more while using significantly less power (memory was limited TBH, but nothing you have said gets remotely close to that being a consideration).
Pi-Hole was designed to be run on a first gen Pi, shockingly they're ancient and largely worthless (eg change hands for next to nothing), running DNS on an actual Pi can be a lot easier and means if you reboot your NAS, you don't loose DNS, if you don't understand why that may be better, then perhaps consider every time you do, anyone else trying to use the connection is likely to call you quite unflattering names, and part of learning invariably means trying things, making mistakes, wiping the lot, reboots and updates.
So, lets try this again, you'd like a NAS/server to run how many drives? You'll be doing what sort of work on it? eg storing media files you write and then play occasionally. Will you be wanting to run something like Plex? The win10 instance you mention, what will that be used for? What hardware do you have? Anything specific that you can think of that you need to run/do that may dictate hardware requirements eg game. Also, what's your budget? Do you hate the person who pays the power bill?
Answer those and you'll get much, much better advice that isn't just a bunch of people telling you what works for them rather than trying to recommend something useful for what you want to do.
