Guys nah tips on how to get an ex back when they’re in another relationship?

[Anonymous]

It ended on good terms and he wanted to meet up again a few week after the breakup but I couldn’t at that point. But now I miss him and would like to find out if there’s any chance left for us. Talking isn’t really an option right now so what things can I do to test his interest to see whether it’s worth opening up the conversation or not? We’re friends on social media (he posts couple pics with his new date on there)