@Mark Brian Douglas now has an experimental open store for multi arch which worked well for me on the Pi. The Telegram UBports Raspberry Pi group is a good place to follow progress.

I know this is about the Raspberry Pi 4 but if any of you, frustrated with the lack of progress, have a Raspberry Pi 3 you may want to try that as it is working reasonably well but with bugs that could do with some attention. Solving them should, in many cases, also help with the Pi 4 once the (compositor?) bug is fixed. Some of the existing UT apps have been recompiled for arm64 so we have working file manager and UT Tweak amongst others. The Telegram group has instructions to add Swap which makes life a lot easier.

Less a question for our too busy main developers (who have been very supportive) than for the wider community. The work on the Pinephone and the ports to arm64 phones has helped get us an image that launches on the Raspberry Pi and software to use on it. However we still need help to get it more useable, particularly on the Pi 4 where the extra RAM should make it a great little development platform for Ubuntu Touch (OS and Apps).

Does any one out there have the time and the skills to help take this forward? There seems to be a good few Linux users with some skills, a Raspberry Pi and a commitment to UT but whose developer skills are not up to finding if a problem is, say, related to the Wayland compositor then working out how we fix that. Whilst this isn't (and shouldn't be) a main focus for the UBports community I believe getting this working well will boost the other arm64 work, help show we are not restricted to a handful of old phones and get us some good publicity.

Even on the Pi 3 Ubuntu Touch is a joy to use, particularly on the 7" touchscreen. I'd happily watch today's Q&A on it if I'd got the skills to get sound playing from the Morph browser in time .

Would the approach taken here (with Gentoo running arm64 including camera, sound and display) work for us or is it too far from the way UT works? https://github.com/sakaki-/gentoo-on-rpi-64bit

@Mark The work on preparing UT apps for other arm64 platforms gives us something to work with now. The UT Tweak Tool seems to work reasonably as does TELEports and File Manager. I can get sound output from the terminal but not through the apps. Mouse behaviour is a little odd and seems to deteriorate - most of my experience is on the Touchscreen which seems more stable and easier to use. Adding Swap has been helpful, particularly when having multiple open tabs on the Morph Browser. If someone can get to the bottom of the (compositor?) issue with the Pi4 the resource related issues should be much reduced, particulatly with the 2 and 4 GB versions.

I realised that that post may look like I'm claiming some credit and that would be wrong.
Early on I did some blundering about in the dark and kept posting about my inevitable failures to encourage someone who knew what they were doing to help - that is the sum total of my contribution

I'm writing this on Ubuntu Touch running on a Raspberry Pi 3 using the OSK on the Pi 7" touchscreen.
Thanks for the hard work put in. There are some issues still of course. Something odd with the graphics in Pi 4 windows and a slight overlap on the touch screen making left or right swipes tricky but this feels so much closer to useable than the first image. I don't think it is too far now from a platform that will showcase convergence and perhaps even let us develop apps live. I appreciate this is a side project so the UBports developers can't make it a high priority. Hopefully though the work done will help towards getting other Arm64 non-Android ports running smoothly. As a long term Linux user - trying to help get Unity8 or UBports working on the Pi has been very humbling - I'd no idea how little I knew/know!

Good to see great progress.
Using the latest image the Pi4 boots and runs well although a graphics issue means that you can't read anything opened in a window.
Scaling is now sorted on the monitor and when using the 7 inch touch screen.
The graphics issue does not affect the Pi3 but it is (understandably) frustratingly slow.
The touch screen worked on the first image but not on the most recent one. UPDATE It woked after a reboot but as the left and right edges are slightly offscreen it restricts its usefuleness.
UT on the Raspberry Pi feels much closer now to something that will work. Thanks to those who understand all this far more than me for putting the work in.

In a few days I will have a Pi4 (4GB). At the moment I can run Marius' image on my Pi3 although the scaling is out (on a HDMI montor and on the 7" Pi touch screen) and it tends to freeze when the browser is run. I got a wee bit stuck until I realised "phablet" was the passcode it asked for