I looked at some supposedly good DAS solutions in the past, but they’re very expensive (300 to 400$) and with limited drive space (4 to 5 drives max). I’d also not take the chance because the onboard USB controller can be flaky and give you issues.
You’re still relying on a solution created mostly for basic peripherals and removable storage, nothing permanent.
This worries me, to be honest. My NAS is sketch city, yet I’d never rely on purely USB storage.