It has the same sandbox support and limitations as Chromium. It supports X11 default in Linux and with limited Wayland support.
It has been tested on M4 macbook and works fine, if you have issues, just post it on the project.
https://wpewebkit.org/about/faq.html
That said this is not upstream Webkit (but they do try to keep up to date, its just they usually lag due to the customizations they did), but a more cut down version of it that supports a bunch of build config flags, and is used by a ton of embedded devices.
It's a fairly significantly more lightweight option to Chrome/CEF, that does suffer from a somewhat worse DX and compat with web content, but if you can tailor your content to it, rather than looking for a flawless ootb experience, it's a worthwhile choice.
I already noticed Webkit doesn't support Wayland on Linux, and some sandbox limitations on Windows.
I assume you're working on improving this? I think I'll just focus on a PoC for macOS right now, and see how that goes!