CodeSpace runs great on Linux! You just need to install Chrome or Chromium browser, and enable the USB device access. Details are shown below:
1. Install Chrome
There are two options here - either one will work just fine for CodeSpace:
Chromium open source browser
> sudo apt install chromium-browser
or Chrome Download from Google
go to https://www.google.com/chrome/ and download/install the package for your Linux distribution.
2. Add a UDEV Rule for the microbit WebUSB interface
a) Use your favorite text editor to create a file:
/etc/udev/rules.d/microbit.rules
b) Edit that file to contain the following:
SUBSYSTEMS=="usb",ATTR{idVendor}=="0d28",ATTR{idProduct}=="0204",MODE:="0666"
c) Signal udevd to reload the rules
sudo udevadm control --reload
sudo udevadm trigger