[Q] Please repackage and Run the emulator file system(system.rfs....

I also want to care about this issue. I have 1 rom, I pulled the file system, for example: system.rfs or system.img.ext4 or factoryfs.rfs. I added, customize the apk and want to put it back and want to be first to run the emulator software to check for errors before running
Core issues, problems I faced
1. how to repackage the system files that (system.rfs, system.img.ext4, factoryfs.rfs, system.img)
2. Using software to run the emulator