please delete

I apologize in advance that I don't know the proper terminology and thus I haven't been able to adequately search for what I'm looking for.

I'd like to have a NAS with a single slot used for a WD Purple for my cameras. In the other slots, I'd like 2+ drives in RAID for my backups. Are there NAS systems that support this? What is this feature called?

Generally speaking, any 'proper' multi-bay NAS such as the big choice of models from QNAP and Synology allow you to configure the drives any way that suits, from JBOD (individual drives) to various RAID levels. There are low-level 'NAS' devices such as WD MyCloud that don't have that flexibility.

But I don't really understand why you'd want to compromise the resilience of a RAID configuration in a multi-bay storage device by splitting up the drive bays.
If it's about storage allocation - the physical drives can be allocated to pools from which volumes of arbitrary size can be configured, giving all the flexibility you'd need for multiple requirements.