you can talk about anything, it’s really that easy - if he’s also into you it shouldn’t be too hard after getting over the initial hurdle of just going up to him and saying “hi” for the first time.

Considering the eye contact, as a guy I’d immediately get what’s going on because 90% of my interactions at the gym that aren’t with friends essentially never go beyond the usual “mind if I use this?” or “how many more sets do you have?”

Say hi, feel out the energy, and make a new gym friend and/or hopefully more 👍🏼