Based on below article, it looks like Yaesu FT-7900E (also likely FT-7800 & FT-8900) can be programmed from Digirig Mobile in CI-V configuration. The cable will look like this:
Serial 3.5mm TRRS tip (CI-V)–> MiniDin6 pin 3 (PTT)
Serial 3.5mm TRRS sleeve (GND) → MiniDin6 pin 2 (GND)
Yaesu FT-7900E | George Smart – M1GEO
This video goes over the programming process with Chirp: