Update:
I started this discussion thread on 2/26 and today, 3/6, I got WSJTX 2.5.4 working on the Pi and Elecraft K4. I am not an experienced programmer but can follow instructions at the command line. To be honest, at first I was not sure if CAT and audio could be implemented on a single USB cable.
I probably would have been successful sooner but stuff gets in the way. WSJTX is working but there are still some questions but unrelated to the WSJTX.
Using "dmesg" was very helpful to have some visibility into how USB devices are recognized and labeled by Pi OS. Some web pages were very helpful for installing. Bottom line is that I tried various approaches like HamPi and Build-a-Pi as well as 32 bit package options.
HamLib was a bit of a surprise to me (as well as "Burr-Brown", "dialout pi" and FTDI. I never paid much attention to it before but I built HamLib 4.4 on the 64 bit version of Pi OS (called Bullseye). I think I eventually built WSJTX successfully. I installed FLDIGI 4.1.20 as well. I pressed toward the latest code in part to try to get the most recent support for the K4 but I cannot be sure it really was necessary. Both WSJTX 2.4.5 and FLDIGI 4.1.20 have the K4 as supported rig options. FLDIGI calls it "K4 stable"
I can say that WSJTX version 2.5.4 on a Raspberry Pi4 4G memory will support CAT, PTT and talk to the K4 such that FT 8 contacts can be logged. This is pretty stable as I have used it. I only use the more basic features so can't speak much beyond making contacts.
In this process I used HamPi and HamPi64beta (probably works fine) as well as web pages and info from KK5JY and KM4ACK and commenters from this forum to plump up my Pi and command line skills, thanks. I also used this website from WT8P for useful information related to setting up the K4 correctly -
I would say FLDIGI 4.1.20 works on the K4 but I have not make a contact yet. It seems fine however, CAT works, PTT works and reception seems fine just haven't made a contact.
In the midst of this the K4 was pulled out of duty and used for a show n tell session at the local ham club meeting. Fun stuff.
I will have more questions but it makes sense to close this thread. Thanks to all who offered suggestions and encouraged me.
*** Ben KE3KQ
KE3KQ