I initially made my portable digi-connection with a RPi-zero, and it worked, but barely. I could not run Fldigi, but found another PSK program that would work, and while WSJT-X ran, the decode time for FT8 was typically longer than the pause between transmissions and so I had a lot of repeats to get the contact made, but it worked. I picked up an RPi zero 2 as soon as they came out and that made a huge difference. I could run Fldigi and FT-8 pretty seamlessly. I did have to get a different case for the Pi as the plastic case retained heat and would shut the Pi off, but with the Flirc case, no such problems. If the size isn't too much of an issue, stick with the Pi4, but I really enjoy the portability of the zero setup and everything runs off a single Li-ion battery and lasts all day. Attached is an article I wrote for a club on my setup.
=Vic=
Vic WA4THR