If i am not mistaken the 253d DOES support addon cards for m.2 nvme. Double check by going to your qnap model page and checking compatible devices.
https://www.qnap.com/en/compatibility/? ... ategory=11
afaik if you want m.2 nvme on your qnap model, this is the only way :X
500gb-1tb m.2 nvme tlc are at good bang for buck prices atm. anything higher than that is usually a premium.
i bought a kingston A2000 for myself it was one of the chespest m.2 nvme out there with tlc and a decent performance with a good price
there are probly other brand models out there but with higher endurance or better performance. but they will likely cost more. do your own research
i recommend checking from youtube and reddit for the best 2021 best on your criteria, performance, budget , endurance, whatever you want to prioritize.just make sure not to get QLC, or DRAMLESS ssds
