possibility of transferring the system in a USB Hard Disk

[cofot28]

I haven't posted in a while but the Library enhancements we are working on will prolly address most of your issues.

Can't you just write the image to an SSD? It should boot like a USB stick providing it's supported by RaspiOS USB boot routine.

Happy to hear your are working on library enhancements.
As for moving the system to ssd, USB 3.0 of Pi4 is fine for this. For instance, Volumio offers this transition to usb hdd as an option  just after instaliling through the sd card.