Wi-fi Latency questions

I’m trying to set up my first Flex in my basement shack. I’ve seen the recommendation for a wired Ethernet connection, but since (years ago) the Direct TV installer cut the CAT5 line I had running to the location where the WiFi 6 router is on the main floor, I have the PC in the shack and another rig connected only via WiFi. The other rig has a Wi-Fi dongle and the PC has built in WiFi. I have tested 15 ms round trip latency on the other rig to a remote server.

My first attempt is going to be to try the WiFi extender recommended on the Flex web site. I could just use the extender’s single wired Ethernet port to the 8600, but I thought for 8600 to local PC comms, I could add an Gig Ethernet switch to the extender output and put the PC and 8600 on wired Ethernet to the switch, which should result in very low latency between them. I am not currently planning remote ops into the 8600, but would like the option if I can avoid re-wiring the house. Complicating matters, my friendly AI search bot says the extender adds up to 45 ms of latency. Would I be better off just adding a dongle to the 8600 and going WiFi into the main router upstairs like I did with the other rig?