I use Whimsical almost every day for process mapping, wireframes etc. Every day I also wish there was a way to navigate solely with the mouse rather than needing keyboard shortcuts or to click other options on the screen in order to pan or zoom.
Miro does this really well by allowing you to pan and drag using the right mouse button and zoom using the mouse wheel.
This is a great suggestion, Kirsten! I also use the mouse heavily and scroll-to-zoom without the keyboard would be a cool feature. You should be able to hold the mouse wheel down to pan around your board already, without the need of the keyboard.
We have an existing feature request for customers who are interested in the ability to customise controls further - so I’ll add a +1 to that for you! 
For some additional context, we’ve optimised mainly for left-handed keyboard short cuts, especially in wireframe mode, to help with speed. You can read more of our thinking behind this on our blog (here) if you’re interested.
Yes, this is the only thing that annoys me about Whimsical. Other tools like Miro or Mural have this covered. Just please copy what they do and make our lives easier.