The analysis of Feature Phones (Keitai) has progressed very well in recent months.
The State of Japanese Feature Phone Preservation in 2023
DoCoMo Debug Cable Preservation Info
Toggle sidebar Keitai Wiki
And it can be run on an emulator. (videos: Rockman.EXE Legend of Network, Densha de GO...
I may try the new ram site, and download more RAM to my Switch. Not sure if ddr3 is the right ram
for it tho. Edit- no it uses floppy Ram, just like @AncientBoi