I have seen a number of posts on here complaining about Gnome-Web and how it doesn’t really work (it doesn’t). Additionally, it is difficult (impossible?) to install web apps using Web.
The alternative I came up with to have Web Apps available is Linux Mint Web Apps Manager tool. I am running Webapp-manager, version (1.2.5). I cannot recall exactly how I installed it. I believe I installed a .Deb file from the latest repository, but I do not remember. I may have asked Apt to download it in the terminal.
Anyway, once I got the correct version installed, it works great. I can install any website as a Web App. I can download and install a nice little icon of my choice from a web search and use that on the Web App. Not every website looks great on a mobile device but using Mobile Switcher extension on Firefox or Chromium works very well.
Thought I would share. Cheers.