If you need a bit of a workaround I managed to get picamera working under Docker on a Pi running the 64bit os. I’d like to get a camera node running in a docker container talking to ROS on the host but I’ve not got around to it yet. The same idea should let you run code that needs PiCamera and MMAL inside a container though.
Picam will work on ubuntu 20.04 Noetic Rpi Arm64 using V4L2 and usb_cam. Won’t work is mmal which is required for the Ubiquity robotics raspicam_node.
@Alan_Federman did you have a chance to try the RoboStack packages? Our noetic support is really good these days: RoboStack: Using ROS alongside the Conda and Jupyter Ecosystems on any Linux, macOS, Windows & ARM
My Ubiquity Robotics Magni is now working on ARM64 Noetic. Two issues to solve were building an mmal library for the camera and moving it to /opt/vc, and removing any architecture requests from ccp programs. Apparently the #ifdef arm directive on a Raspberry Pi 4 on the ARM64 Ubuntu image comes out as false.