Yes, you can use the KATANA:GO even while charging.
KTN-GO and KTN-GO2
There are two different external designs for the KATANA:GO corresponding to the period in which they are sold. This manual only features illustrations for one of these designs, but there is no difference in functionality or sound quality between the two. For details, see “About the external design of the KATANA:GO” (BOSS website).
https://roland.cm/katana-go_om
https://roland.cm/katana-go_om