Thanks! I was able to fix this but will do those steps anyway just to make sure. A kind soul on the doom emacs discord server used my problem as an excuse to learn more about the kernel modules and was able to help find a solution.
https://bugzilla.kernel.org/show_bug.cgi?id=193121
It comes down to the particular WiFi chip I have, Broadcom 43602 just not really being really well supported by the firmware itself. Fortunately, someone came up with a workaround in the form of a config file that can be copied into the /lib/firmware/brcm/. Instructions may be found near the bottom of that link:
https://bugzilla.kernel.org/show_bug.cgi?id=193121#c74
Which is a small enhancement on top of 193121 – brcmfmac working extremely poorly on MacBookPro13,*.
With that latest text file copied to /lib/firmware/brcm/ and a reboot I am now able to connect to my 5 Ghz network and see many more networks in the list.
As for why those changes and others are not upstreamed, correspondence earlier in the discussion https://bugzilla.kernel.org/show_bug.cgi?id=193121#c23 provide some insight:
The firmware update is not an easy task as it updates regulatory data in firmware it means a full verification cycle is required to assure the power levels stay within regulatory limits. This is always a hard sell for us as there is no return of investment for the engineering costs involved. Hence we release fullmac firmware that has been verified in running projects. Sadly the 43602 in the MacBook does not use a fullmac driver architecture so there is no fullmac firmware available. I have forwarded your request, but no high hopes we can resolve this.