We are experimenting with the ability of having one 64 bit kernel to automatically boot the RPi's 3b/3b+/4b depending on which board you are booting up on.
We would appreciate it if some of you that have the time and like to experiment help out with testing to get all enabled in the kernel that needs to be for things to work. For example I ran across where the cpu temp did not work on the pi3b and had to enable CONFIG_BCM2835_THERMAL=y.
I have made an image for testing with using the LXQT DE with VC4/V3D enabled. This will be a good image also if some one has a pi3b/pi3b+ to use as I have a swapfile to free the ram of data not being used. I have also fixed some things in LXQT that was not working. I am using chromium browser as it has an edge over firefox with webgl.
What we have with the kernel is now in the repo (4.19.81-1). It has gpu_mem=64 in /boot/config.txt. Since being in VC4/V3D mode you may want to try gpu_mem=32 and see if it makes a little better. I tried gpu_mem=16 and it was at the threshold of not being enough so I am testing wit using 32 right now and seems to be ok so far. the gpu_mem does not need to be much when using VC4/V3D as it uses cma=256.
Download the image below burn and boot it and go through the OEM setup Then try the image on your various 64 bit pi's you have. The slower the pi is the slower things will load up initially; just wait on it. The same applyies to loading up the desktop at first; just wait for everything to load up first then the desktop navagation should be smooth, With the web the same with a web page loading up.
Advise not to use libreoffice or open multiple web pages / desktop windows while using the web browser with the 1G ram boards to conserve resources. Also a really good high speed sdcard.
Thanks in advance for anyone that has the time to help and provide input.
Here is some screen shots hots using the pi3b I used for testing:
mpv playing a 18 Mbit ATSC 1920x1280 stream: