I think time will tell. A lot of suppliers are playing "catch up" with Triumph on this (which is a shame on Triumph). There are no aftermarket products (that I can find) for the R3TFC, R3R, or R3GT.
I was looking for a K&N Air Filter to swap out the stock filter. Doesn't exist.
To get a handle on things, I was also looking for replacement brake pads, front and rear. Things to know when you get stuck in the middle of nowhere without a Triumph dealer nearby. No joy there either.
I suspect this will be true for seats, grips, exhausts, and other changeable parts.
I am glad to hear you called them and got a response! Maybe you put the idea in their head!