How to find nearby public restrooms?

Partner and I are visiting Portland for the first time in a few months and we have a good idea of where we'd like to go see. (One day would be in portland proper, the other would be taking trimet into Beaverton/Cedar Hills, then Orencho Station/Hillsboro.) We'll be getting off and on the trimet throughout the day and the goal is to see different neighborhoods through Oregon. We are getting a good preview before we decide if we might want to move or not, much later down the line.

I have a weak bladder and typically need to piss about once an hour. Since we are planning to get on and off trimet for 6-8 hours ish, I know it will be super important to find bathrooms within walking distance throughout the day. Any advice on which apps/websites to use to easily find public, working bathrooms? Also, if you can just name drop some bathrooms that are conveniently along the blue/red lines, that would be helpful. Thanks for any advice.