After months of looking for this seemingly elusive tool that scalpers online like to charge 2x for, I finally found 1 in stock at my local HD : r/ ryobi
RYOBI 18-Volt Cordless Heat Gun Kit with Battery (Bulk Packaged, Non-Retail Packaging) Charger Not Included - Amazon.com
Cordless Heat Gun | RYOBI R18HG-0
Milwaukee M18 Heatgun (Naked) M18BHG-0 | Euro Car Parts