Find all pages on a site with no hyperlinks

It happens with me that I find a useful/interesting website but it's a one-page application with no hyperlinks. Only when you know what "path" to add after the base URL that you can explore other pages. Although websites like these should have a homepage, the fact of the matter is that they don't.

For example, I found this site - it helps understanding how the human voice works: https://dood.al/pinktrombone/ and it's brilliant. Now, I thought are there other web pages like this on the same site. I went to its homepage but no luck, the homepage has another application.

I tried Googling "site:dood.al" which helped me find an oscilloscope application[https://dood.al/oscilloscope/] but is there is a more reliable way of finding all valid complete URLs given a site.

It happens with me very often that I find these sites but no way to navigate on the website.