I have the same case for my SFF work pc. Its great, but the front dust grill can be a pain to clean and service.

For the M.2 slot. I believe the E key is for WiFi modules. However, you should be able to buy an adapter for M key. Something like thisSintech M.2 (NGFF) NVME SSD to M2 A/E Key WiFi Port with 20cm Cable https://amzn.eu/d/3JG3dhO ( YMMV - I've never used this setup for a boot drive before, please do your research before purchasing!)

In my opinion, I would still recommend purchasing a standard SATA ssd. If you find the nvme adapter works and you can have it as your boot drive, you could always use the SATA ssd as a cache store for the spinning rust

Having the same post appear several times in your feed also doesn't help and the general lack of engagement often makes lemmy feel like a ghost town.