If you only met few times it’s too early to call them friends.

They don’t particularly know you well enough to show interest in your travels and it’s unlikely they are jealous. I am not surprised they didn’t make arrangements to meet in person to see pictures.

In addition most people don’t find it exciting to look at travel pictures of people they barely know. Not because of jealousy but because it’s not interesting if you aren’t invested in their lives.

I don’t know if they are self absorbed. It could be. But could be also that they are mostly just strangers and can’t be expected to show interest in people they don’t know on a meaningful level. You could try to take it slow and get to know them as friendships take long to build or you could try to make friends irl instead.

You have to build a foundation for friendship and it takes time