When the new Studio comes, RESIST the idea to set it up immediately and boot it.
Instead, do this:
On the day it will arrive, do a "last backup" on the Mini.
I recommend either SuperDuper or CarbonCopyCloner for a cloned backup, but it you use time machine, it will do.
When the Studio arrives:
Take it out of the box, put it on the table, connect mouse, display.
BEFORE you push the power-on button, connect your "last backup".
NOW push the power on button for the first time.
The Studio will boot and you'll get to the initial setup screen.
Begin setup.
At the appropriate moment, setup assistant will ask if you wish to migrate from another drive or Mac. Yes, you do, so...
"Aim" setup assistant at the backup drive and give it sufficient time to "digest everything" (it will take a while).
When done, setup assistant will present you with a list of things that can be migrated.
I suggest you "accept the defaults" and migrate everything.
Turn s.a. loose and let it do the migration.
When done, you should see you old login screen, just as it appeared before on the MIni.
REASON WHY I suggest a "full migration":
The m1 Mini is "not that far behind" the new Studio.
I'll take a GUESS that most of the stuff you have now will be "still working and up-to-date". Perhaps not everything, but "most everything".
Good luck.