Looking for a gravel/road bike

Hello fellow cyclists, a little insight, I am 42 yo male, overweight and I bought myself a nice 12yo Specialized Stumpjumper last November. The idea was, I love powerlifting but I hate cardio in the gym, so lets go outside. Little did I know... after the first butt aching ride the little full sus bugger grew so much on me that within a month I was getting up at 4 am to leave the house and watch the sunrise somewhere cool 30Km away.

Eventually I came across other cyclists and, while I am a loner I do enjoy group rides also, these boys are all on gravel bikes and between stops eventually they told me I should make a switch in order to be able to keep up with them on 90 + km rides. Is this so?

One thing I notice is I seem to be in a lot more effort than they are during rides, and past the 70Km mark I usually tell them to go because I need to take it slower and I really don't like people waiting on me.

I previously assumed this was about sheer conditioning or athleticism which aparently it might not be the case.

I seem to have found online what I think is a good deal and I should not let it slip and need some other opinions.

It is a Canyon Grail CF SL for 1400€, carbon frame, discs and Shimano transmission and brakes.

The bike seems well looked after but it is 300km away from where I live and to make the "inspection" trip I need an opinion on wether this might be a good deal or not.

Thanks all in advance