Good afternoon Loyd, Kari, and Bill - thanks to all for your suggestions.
I have WSJTX 2.5.2 installed and working on multiple OS Buster / RPI 3 and RPI4s. I will try the build procedure on an RPI4 with Bullseye soon.
There were no other applications running except nano for me to read the build instructions from the INSTALL file.
But I wanted to add it to a new RPI Zero W2 I have recently received (as much as anythng to try to run the build from source process).
Yes Bill, the RPI Zero 2 W has only 512 MB of SDRAM - if that is too little to allow the build process to run then so be it - it was worth a try (and a learning exercise for me).
Have a great Thanksgiving tomorrow (you can enjoy it with us if you like Kari and Bill!).
Edd - KD5M