Chiming in on the topic of 3rd part developers taking some of that weight:
I've been contemplating making a brand new Steam NW.js plugin around the new steamworks.js which seems to be much more actively maintained.
My main issue right now is that I have never used the lib before and I don't have much time to learn it, and don't think I will have much time for it for at least a few months.
That being said, if someone else has time for it, we've recently set up an Open Collective to crowdfund Free Open Source 3rd party stuff for Construct with some folks in the Construct community.
I invite any dev that would be up for the challenge to reach out and we can set up a project for them (we've already funded one project and others are on the way)
opencollective.com/construct-community
That way everyone could chip in to fund the development of this new plugin and it could resolve that issue, while also avoiding long term issues that come with important addons like these being closed source and abandonned after a few years.
On an unrelated note, I would also like to add that indeed the lack of File System access for the WebView2 export is sad. I already advocated for Tauri as an alternative to a custom export maintained by Scirra as it would make developing addons for it much easier. Tauri has the same benefits as the Cpp WebView2 export, but also has full File System access (as well as a bunch of NW.js equivalents) it also has cross platform support, and lets you write Rust which means extending the app with native stuff (like steam support and such) much easier for 3rd party devs.
I understand that using Tauri might also come with a bunch of challenges of its own. Also Tauri suffers from the same issue Ashley's WebView2 wrapper has with Steam overlay.