I’d be happy with just a field where I could input the remaining grams whenever I load a spool to preset the value, then have an odometer update from there. Make a note of the number when I remove a spool, re-enter it next time.
Ideal would be to allow manual input to the spool ID database. To be safe, they’d probably need to add a boolean field to the DB, to indicate Bambu Native vs Foreign, but once that was done, the user could just enter whatever numbers they wanted to track their spools. When loading a new spool, you could tell it was a new 1kg spool and give it a number, then just use that number when you unload/reload it.
But really, just a manual input for remaining-filament for non-Bambu spools would be a huge convenience and I wouldn’t think too difficult to add. (End users never think anything is “too” difficult 