GUI for managing fingerprints/PAM that allows complicated or at least some customization with PAM such as requiring password on first login then allowing graphical fingerprints for sudo, unlock and other prompts with fallback to password.
1GB is probably enough to run one basic service without a GUI. If you want anything more than that you’re going to probably end up running out of RAM and hitting the SWAP file–grinding everything to a snail’s pace. Useful projects here might be to add smarts to something dumb around the house or making an old printer support wireless printing via cups.
Like others have said if you want to tinker, a virtual machine via virtualbox or VMware is free for your use case.
If you strongly prefer hardware, an old PC will probably be cheap or free.
If you really want a pi you’ll probably have to look for something that has at minimum 4Gb (which will be easy to outgrow), recommending 8GB+. Note that raspberry pi’s run best on the official power plug as a USB-a to micro/c won’t provide enough power to be stable and will cause weird issues or crash the pi under heavier loads or when drawing power from the pins.
I googled the echo flex and I don’t see any evidence someone has gotten the bootloader unlocked or have been able to install a custom ROM/OS. Depending on the generation the flex is based on, it could be Linux or android based. Have you been able to access the os on your devices? If not, you might have a lot of work on your hands to get enough access to install any kind of non-stock OS.
My understanding is that hba cards support virtualization better than passing sata directly through. But if you’re not virtualizing the NAS, I wouldn’t see an issue with a reputable motherboard that has enough sata ports at 6 Gbps.
For the cheaper expansion cards I’d see that as a central point of failure and would recommend an hba card over a cheaper alternative.
So Linux is a collection of different software, companies and volunteers. If you think of cars Linux is basically a paper design of an engine that anyone can use for free. Then Ferrari, Toyota, ford and all the other companies build their own physical engine on top of that. Some of the companies have “dealerships” or support but they primarily cost a lot of money and cater to companies, not people. There’s no Linux store the way there would be an apple or Microsoft store.
The comments here are right, in that most computer repair shops should be able to figure it out the same way you can take almost any car to almost any general mechanic. There might be some complicated issues that requires someone who’s good with that specific brand, but a basic install isn’t super complicated in the same way changing the oil on a car should be straightforward for all mechanics.
Since you’re in a rural community you can either do it yourself, try to find another computer repair shop, or ask a friend/family member nicely in exchange for food, money, whatever (please don’t assume this person wants to be your dedicated support person). Linux is great and it can be pretty straightforward if you dedicate some time to learning.
If you do it yourself or have a friend do it: