eco-friendly whipping siphon
There may be a siphon manufacturer that makes a pump model that doesn't use chargers, but I have never seen one and I can't find evidence of one online. 

The most eco-friendly route would probably be to whip the cream with a mixer and use a pastry bag to pipe it onto things. You could either use a reusable bag or disposable bags which should be more easily recyclable.

Edited to add: There are countertop whipped cream dispensers that do not use chargers. You add cream to a cavity in the top and they dispense from a nozzle in the front when a button is pressed. These require counter space and electricity though, so they're not practical for everyone.