Building 1st pc - unsure on mobo & ssd + pci5.0

Hey, will be building my first pc, been wanting to do it for some time but unsure on some of the parts. I’m recycling some stuff from a couple pcs I have.

Here’s what I’m considering so far:

CPU - 9800x3d GPU - RTX4070 12 Gb Gddr6 dlss3 Case - Forgeon Mithril ARGB Mesh ATX Tower Black PSU - Forgeon Bolt 750W 80+ Gold RAM - Corsair 2x16gb cl30 6000 MOBO - SSD1 - SSD2 - SSD WD BLACK SN770 1 TB PCIe Gen4 NVMe Network Adapter - ASUS PCE-AX1800 PCIe AX1800 Wifi 6 bt Cooler - WATER COOLER CPU NZXT KRAKEN 240 w/ DISPLAY + Arctic p12 120mm fans

I’m really unsure about the mobo mainly and perhaps the SSD which will have the os.

For the mobo, not sure out of these Msi b850 tomahawk Msi x870 tomahawk Msi x870e tomahawk

Main reason being the extra pci5.0 slot. One will always be for the gpu I guess. Not sure if the extra price is worth for the second pci5.0 slot for the ssd. Will it make a difference? Is it worth preparing for the future and paying a bit extra?

For the SSD, uncertain between Wd black sn850x Samsung 990 pro Something gen5 for above like crucial t700

Any help would be highly appreciated!