Question B350 boards and SATA SSD on Ultra M.2 and M.2

[anthia]

Hi, I'm kinda confused in terms of storage specs on mobo with B350/450 chipset.
For example, AB350M Pro4 R2.0:

• 4 x SATA3 6.0 Gb/s Connectors, support RAID (RAID 0, RAID 1 and RAID 10), NCQ, AHCI and Hot Plug*
• 1 x Ultra M.2 Socket (M2_1), supports M Key type 2242/2260/2280 M.2 PCI Express module up to Gen3 x4 (32 Gb/s) (with Matisse, Picasso, Summit Ridge, Raven Ridge and Pinnacle Ridge) or Gen3 x2 (16 Gb/s) (with A-Series APU and Athlon 2xxGE series APU)**
• 1 x M.2 Socket (M2_2), supports M Key type 2230/2242/2260/2280 M.2 SATA3 6.0 Gb/s module

*M2_2 and SATA3_3 share lanes. If either one of them is in use, the other one will be disabled.
**Supports NVMe SSD as boot disks

This one is clear to me, on Ultra M.2 socket I can only run NVMe SSD and on M.2 socket M.2 SATA SSD (3 SATA lanes left).

But there is AB350M-HDV R4.0 :

• 4 x SATA3 6.0 Gb/s Connectors, support RAID (RAID 0, RAID 1 and RAID 10), NCQ, AHCI and Hot Plug
• 1 x Ultra M.2 Socket, supports M Key type 2242/2260/2280 M.2 SATA3 6.0 Gb/s module and M.2 PCI Express module up to Gen3 x4 (32 Gb/s) (with Matisse, Picasso, Summit Ridge, Raven Ridge and Pinnacle Ridge) or Gen3 x2 (16 Gb/s) (with A-Series APU and Athlon 2xxGE series APU)*

*Supports NVMe SSD as boot disks

So... can I connect 4x SATA SSD + 1x M.2 SATA SSD into Ultra M.2 socket and boot from M.2 SATA SSD?

 

[rgd1101]

you can change boot seq to any bootable device in bios

 

[anthia]

you can change boot seq to any bootable device in bios

Ofc but what about booting SATA SSD from Ultra M.2 socket?
"*Supports NVMe SSD as boot disks" means "Back in the days you could only boot from SATA SSD, now also from NVMe" or "Ultra M.2 socket is bootable ONLY from NVMe device"?

More important, can this mobo handle 5x SATA devices which means there is 5x SATA lanes?
Every overview about B350 chipset says 2x SATA III + 2x SATA III or 2x PCIe 3.0