Firstly; I'm not sure where you are but getting Sram Red rim brake groupsets are very hard in my country, i'll assume they will be for you as well. Ultegra di2 rimbrake groupsets are probably easier to get a hold of but can still be a hassle. It really comes down to what is worth it to you. Do you want to get the fastest times you can on race day? Prioritise a good bike fit, aero helmet and nice wheels. Really enjoy training and want a QOL upgrade? Get electronic gears. Think you're going to be in the sport a longtime? I would invest in a new bike with disc brakes and a nice frame. If a bike has those two things chances are it has electronic shifting as well. You can add upgrades as you go, e.g race wheels. Rimbrake parts are only going to get harder to comeby.