How to use WebApps with Firefox/snap?

In Linux Mint project they developed the interesting WebApp application that for particular web page (mail, messengers, etc) user selects can be used like independent application, not requiring to open web browser for such web pages.

I followed the article to install WebApp but “+” button to add new web site is grayed out. According to the article’s note this is because Ubuntu 22.04 is using Firefox/snap and WebApp does not recognizes the browser.

It there a way I can make WebApp to recognize Firefox/snap?

I don’t want to install another browser to do the job.