You appear to have covered the device formatting requirements. Note that you you’ll not be able to use an encrypted drive when using anything other than APFS.
The remaining consideration is power. Most USB storage devices require more power than an iPad can supply via its Lightning port. To use external storage, you will need to use either an appropriate adapter - or a powered USB hub.
If using an adapter, you will require an Apple Lightning to USB 3 Camera Adapter:
https://store.apple.com/xc/product/MK0W2ZM/A
This adapter has both a USB3 Type-A port to connect external USB devices - and a pass-through Lightning port with which to connect a Power Adapter rated at 12W or greater. While this is the correct Adapter, there have been a small number of reports that the iPadOS 16.5 update is not working as expected with this adapter; current speculation is that this is a bug.
If you have not yet updated to iPadOS 16.5 (released yesterday), the adapter should function normally.