Not sure if you can. Maybe a stand alone sear burner.
Here is my 2 cents. I have one grill with a dedicated sear burner (Holland Apex). My kids bought it (sear burner) for me. It attaches on one side of the grill. Is it nice? Yes. Is it needed? No.
I have come to appreciate how a Holland Grill cooks. It just chugs along between 420-440°, only temp control is on/off. So in reality I only use it when the kids are here.
Your Lynx is a quality grill, should get plenty hot for a sear (might struggle in the winter).
Now my AOG you could add a sear burner when I bought it BUT you needed to add a firebox liner (kind of made it double walled), maybe Lynx has/had that requirement and thats why the parts guy is waiving you off.
Hey, good thought but not sure if I want to clutter cooking area. I need allot of room... I reviewed a break down of parts from the partition to the gas deflector and seems pretty simple. Ignitor can also be different depending if Pro Sear or their Trident. Just hate making a morphydite but not many will see her.
I can’t speak to Lynx, but it seems odd there is not an easy path to adding a sear burner. My wife bought me a sear burner for my Artisan Pro as part of Christmas gift giving. It’s specific to Artisan grills however, and comes with a modified ignition lighter for the sear. The Artisan gets extremely hot, and I agree it’s probably overkill. Still, it seems pretty nice and I’m anxious to get it installed.