UPDATE: Some people have reached out to me that the guide does not work for them. I've decided to re-do the guide with a clean install of Debian 11 Bullseye (stable as of August 2021).
MySQL Workbench is currently unavailable on Debian 10 and 11. Ubuntu packages seem to be incompatible. The only two remaining options for installation are: getting a Snap package or building the Workbench from source. This blog post deals with the latter.