Router for domain.com/a.apk

Hi.

SHORT STORY:

I want to catch that the address is domain.com/a.apk with a router and redirect it wherever I want. I am trying to use router but as I know I can only use routers with a prefix in url. What kind of router can I use to catch domain.com/a.apk address?

A similar problem is here but no solution is finally given: https://www.wix.com/corvid/forum/community-discussion/redirecting-pages-with-symbols-in-name

LONG STORY:

Before I decided to use wix I had an app file (a.apk) for my customers so they could download it. There are about 10000 people who know this address (domain.com/a.apk).

Because I am using wix, now it works like:

  1. I created my own error404 page with a “Download button”. So when anybody put domain.com/ANYTHING and (so also domain.com/a.apk ) they will see the button and they will not be confused where to find the app file.

But in the above solution I change the logic of error404 site which I do not like. So:

The question is: is it possible to:

  1. Create a router that will catch that the address is domain.com/a.apk

so I could:
2a) redirect it to a file on the other server.
2b) redirect it into a page domain.com/download and there I will put the “Download button”.

I am waiting for your suggestions.