You're getting a lot of answers from people who don't race. I don't know if you can take a lot of responses seriously.
Look for a sub 20lb bike that can fit 40's. Good chance this means carbon but can be done with wise wheel selection with aluminum also. You probably want higher gearing and smaller steps. 50-34 or 46-30 would both work but you need to plan on 35mph. A lot of 1x probably can't do that.
I may have a minority opinion here too but 105 or GRX 600 is the absolute bare minimum to use. Less than that and performance might get in your way.
Experiment on gravel courses. Some are dusty road rides, a 28-32mm tire probably is faster. Others are a little less civilized, and pushing into 40 and beyond might work. You need to figure it out what you like. Tubeless, no brainier.
Single seat bag, tube co2, levers. The big stuff is for bike packing and epic solo rides.
Does that cover it?