A small step for Vice, but a giant leap for 3DS, this is. Thank you.
I ran some tests.
1) Alternative system ROMs like Jiffy DOS for faster disk loading (10x) and improved BASIC commands work now.
In order for it to work you must
a) in settings, go to DRIVE, Drive 8 settings, and double check that 1541-II is selected as type
b) Still in DRIVE settings, ensure that True Drive Emulation is ON, and Drive Sound Emulation is ON (fun).
c) Still in DRIVE settings, go to Autostart settings, and DEACTIVATE Autostart warp
c) go back, and then to Machine Settings, then ROM settings, then Drive ROMs, and select the appropriate JiffyDOS ROM .bin for the 1541-II floppy drive which you have sourced from somewhere. You can also install, while you are there, the ROMs for all the other drives like 1581, as default ROMs
d) Go back, and under Computer ROMs, select Kernal, and select the JiffyDOS C64 ROM from your collection. No other ROMs need to be changed.
e) Go back to main menu. Go to Settings management, and save current settings. If you don't do this, you will have to do all of the above again next time you load the emulator.
f) Restart the emulator. For some reason JiffyDOS will not really kick in otherwise.
As a result you will have a fast disk loading that is truthful to C64, without warping, and it's 99.999999 compatible. JiffyDOS also has improved command functions:
https://www.c64-wiki.com/wiki/JiffyDOS
2)
Screen button (widgets) and virtual keyboard
a) They cause some kind of distortion if used. You will notice if you run software that uses sound. For example if you press any of the widgets, or keyboard keys like shift, there is a distortion. Ideally, this kind of distortion wouldn't happen
b) the Load "*", 8,1 should be followed be the RUN command to make sense.
I have some more observations and ideas but that's it for now. Very grateful to see this emulator developing nicely.