Bluetooth support is available in KatanaMan and GT1Man, GT1BassMan, and GT1000Mate (beta version). This enables connection to the Boss device without requiring a USB connection to your phone/tablet. The connection relies on the use of a compatible MIDI/USB adapter (except for GT-1000 which uses the in-built bluetooth support) .
The CME WIDI Uhost product has been validated for this purpose, and you can find the CME Uhost here:
https://www.cme-pro.com/product-category/ble-midi/widi-uhost/
For Katana, the XSONIC AirStep Kat has also been validated and is fully supported, and you can find it here:
https://xsonicaudio.com/pages/airstepkatedition
Details on how to set up a Bluetooth connection can be found here : How to use Bluetooth to connect to Boss Katana or GT devices