I've got an idea how to get WebKit work beautifully with Ubuntu Touch, I hope @WPEWebKit are willing to merge these changes once finished.
It consists of a new backing store + IPC passing of gralloc/libhybris buffers in WebKit to efficiently do graphics on our beloved platform.
This should help us get our new in-development browser for Ubuntu Touch to the performance one expects. :)
@fredldotme have you looked at the new WPEPlatform companion library that we have been working on? Ideally the lower level buffer sharing mechanism for libhybris would go into libWPEWebKit (if needed) and then the rest of the support code for would go into a platform implementation for WPEPlatform. You may be able to reuse the WPEQt binding we already have as well, the new code supporting Qt6 is already using WPEPlatform these days.
@fredldotme at any rate, if you have any doubts, please stop by our chat room, reachable via Matrix at https://matrix.to/#/#wpe:matrix.org or via the #wpe channel on the OFTC IRC network—we'll be happy to discuss specifics and try to help you doing something that would be suitable for upstreaming and hopefully easier to maintain in the long run 
@WPEWebKit I'll join soon, thanks for the invite! Is that WPEPlatform library outside of WebKit sources? I have a clue where to start but more correct information is always welcome :)
@fredldotme the WPEPlatform library is included in the WebKit source tree: https://github.com/WebKit/WebKit/tree/main/Source/WebKit/WPEPlatform — the API is in flux and will still receive some changes, mainly around adding a “top level” concept: a container for a set of web views, where one of them is displayed. After that it will be mostly polishing.
We are trying our best to get it ready for the 2.46.x release series (the next one, due in September), at least in beta preview quality.
@fredldotme as for the Qt6/QML platform implementation that uses the new WPEPlatform machinery, you can find it here: https://github.com/WebKit/WebKit/tree/main/Source/WebKit/UIProcess/API/wpe/qt6 — the idea is that almost anything dealing with platform integration will go through WPEPlatform, so we can phase out using libwpe+wpebackend-xyz in the future.
The only exception are buffer sharing mechanisms (DMA-BUF, AHardwareBuffer, etc.), which we now have inside libWPEWebKit to take advantage of WebKit's internal IPC.
Hopefully this helps follow! 
