Does Ubuntu Mate 20.04 support USB booting on Pi 4?

Just wondering if I write Ubuntu Mate 20.04 64-bit directly to a USB flash drive, can I boot it on a Raspberry Pi 4? Mine is the 4GB model, BTW.

Wimpy has stated that this is currently not supported for Ubuntu on Pi4. Support will be coming from upstream and the ETA for that is not known at this time.

I was able to load into Ubuntu mate using the USB by flashing the image on both microSD card and USB. You need to rename the writable partition on microsd card to something else and it will boot through microsd and use the USB writable partition. However I do have issues with the WiFi as it doesn't seem to ever recognise the device. Does anyone know how to get the WiFi to work? It may have something to do with that bug from initial setup not reading the WiFi.

I also have this kind of trouble at first, but after I switch to only microsd to boot and install the ubuntu mate again, then use usb and microsd card to boot, the network and bluetooth trouble magically solved. i really don't know why but i think that maybe helpful

I have root mounted on a USB connected SSD drive and wifi/BlueTooth are working. I did not copy the contents of the root partition until after all the first boot stuff completed. I think the partition resizing has to complete before wifi and BlueTooth are setup.

It's simple. Bootloader has kernel. It has board specific information. You can call it bios. It has information about all devices and how and where are they connected: CPU, memory bus, pci-e ... So if you use rasbian's bootloader too boot Ubuntu of course it would not work or something like wifi or eth0 would not find it's driver.

Now it's enable on raspberry os, is it possible on ubuntu mate for rpi4?