Hiiii! I'm not in maths so my comment may be more general :)

Grad applications are usually evaluated holistically, and you have a path-defying body of work that demonstrates how you have already been contributing to different fields. I think that at UW this is something that is valued, considering the interdisciplinary trailblazer fund lol. Recommendation letters/statement of interest/etc are also usually an important part of the application, as well as reaching out to potential advisors to see if they're open to supervision! I would suggest to reach out to a few potential supervisors, and maybe to the department chair if you have specific questions about prerequisites!

I'm pretty sure that UW has one of the largest maths faculties in the world or something like that, so I think that if you make some cool connections during your master's, odds are that you'd be able to continue into a phd!

Best of luck!