Haven't seen a lot of examples of boards that implement the GA-FC, so here's the one I just put together! (Also posted in r/guitarpedals) : r/ BossKatana
Pre-Owned Boss Katana 100 MkI with Footswitch - Five Star Guitars
Boss GA-FC EX Foot Controller Price $149.99 - Victor Litz
Boss FS-6 Dual Foot Switch - 761294086513
Boss Katana 50 MKII 1x12 Combo with FS6 Footswitch at Gear4music
Amazon.com: Boss GA-FC EX Foot Controller for BOSS Katana Amplifiers : Everything Else
KATANA Ultimate Footswitch | AIRSTEP Kat Edition – XSONIC
Amazon.com: Roland GA-FC Foot Controller for GA-112 and GA-212 : Musical Instruments
The GA-FC: Unlocking Performance Potential with Your Amp
Custom Footswitch prototype for Katana MK II : r/BossKatana
Using a Roland GA-FC footswitch with Boss Katana 100w amplifiers - YouTube
Custom Boss katana 50 footswitch Alu | Reverb
BOSS Katana-100 Guitar Amplifier and Single Footswitch Kit B&H
Supercharge the BOSS Katana MkII with the GA-FC EX - BOSS Articles
Amazon.com: XSONIC Airstep Kat Edition KATANA MkII & I Footswitch with 5 Footswitches, 2 Control Modes(Change Presets, Toggle Effects), 300H Playtime, Modify Amp sound with BTS App for iOS and Android, Wirelessly :
Boss Katana-100 MkII 1x12 inch 100-watt Combo Amp | Sweetwater