Texas holdem with an overall time limit
I have not seen anything for an official rules for a time limited game but I have played in settings where there was limited time and players would come and go as they could.

In those situations we would set the chips and the buy in to an amount that can easily be converted back and forth. For example we would set chips to mirror coins (down to the smallest amount you want to deal with) and at the end of the night (or when someone needs to leave) they cash out for how much they had in chips at that time.

Since the games are just for fun there won't be a rush at the end to get a few more chips to win it all but just a general progression to try and at least break even.