I am setting up some projects in Trello with multiple lists organized in a way that we are focusing on one or two lists at a time. I there a way to filter so that the ones we are working on are the only ones visible?
No. But see How do I hide and show entire tasks lists in Trello? , which has
".. there is a feature request called Collapsible Lists which you can support by e-mailing email@example.com."
I'm in the same need ang my google bring up this helper used in Chrome
There is a list filter extension that works for me.