A Python script on my Android phone computes the above. I might write a native app later. I'm also thinking of making something at my desk that emulates a USB keyboard that I plug into my phone with an OTG cable to enter the computed password automatically.

For less-sensitive sites (i.e. things that aren't going to screw me over if my account is hacked), I just save the computed password into the Chrome password manager. The computed password can't be feasibly used to get my master password anyway.

For many sites it's possible to stay logged in with a session cookie without saving the password.