Audio production pc build: question about lane sharing

Hi all,

I'm trying to build an m-atx pc for audio production. That's why this build prominently lacks a dedicated graphics card. See the build in the table below.

I feel pretty confident about it, but I do have an important question regarding the motherboard (ASRock B850M Steel Legend WiFi). I need to know if the m.2 slots share lanes with any of the pcie slots, especially the bottom pcie x4 slot, since I want to use that one for a firewire pcie card while at the same time using all 3 m.2 slots.

I can not for the life of me find any explicit statements mentioning any lane sharing behavior. Please, if you can help me figure this one out, I'd be very grateful. Of course, feel free to comment on the other components as well.

Bonus question for pc+audio nerds: Does it matter in which m.2 slots i put the three ssd's?

Thanks a lot!

|| || |cpu|AMD Ryzen 5 7600X Processor| |mobo|ASRock B850M Steel Legend WiFi| |cpu cooler|Scythe Fuma 3| |memory|Patriot Memory Viper Venom 2x32GB 6000Mzh CL30 PVV564G600C30K| |ssd 1 OS + PROG|WD Black SN7100 500GB M.2 SSD| |ssd 2 PROJECTS|Lexar NM790 2TB M.2 SSD| |ssd 3 LIBRARIES|Lexar NM790 2TB M.2 SSD| |hdd BACKUP|Western Digital My Passport external hdd 5 TB black| |case|Lian Li A3-mATX Black| |case fans intake|Arctic P12 PWM Black| |case fans intake|Arctic P12 PWM Black| |case fans exhaust|Arctic P12 PWM Black| |psu|be quiet! Pure Power 13 M 550W PSU|