Triathlon can be very expensive. It can have a lot of “noise” from advertising. As a beginner, you will be bombarded with you need THIS and THIS and THIS and THIS. You don’t. Don’t be roped in. I was and it was a mistake. Don’t fall for it.
What you need for a triathlon:
Swim: goggles, swim cap, suit, wetsuit (if outdoors and cold enough) Bike: a bike with two wheels and pedals that rolls, a HELMET, shoes Run: shoes
No need to make it anymore complicated than it needs to be. If you can splurge on the fun stuff, do it. I’m guilty in some aspects. But don’t let the new best and greatest invention and the advertisers telling you that you need it to keep you from doing a triathlon.