Really depends on what you want out of the system, what you can spend and how much time you want to spend on it.

My old z390 itx system has a 16x PCIE to 4x m.2 card - leveraging an m.2 to 5x SATA adaptor with the built in SATA adaptors has given it plenty of space.

Considering I can grab m.2 to 6 SATA adaptors and fill the remainder of the slots that’s a decent chunk of drives from a single PCIE x16 slot.

Software is another kettle of fish and a good way to timesink, I’d rather not give too much of my personal experience as there are so many ways to skin that cat.

Works great and has been for some time on my P7P.

Ensure you’ve allowed background usage and turn off manage app if unused.

Keep the notification on and allow notifications.