Going to the list of supported devices and doing a stupid count (-> document.querySelectorAll("table.device tr") - I didn't see a count after a few seconds, so..), I'd say it's a bit more than a handful. :) 237 unless I messed up.
The only problem then is typically getting it all to compile will be many person-months of work. There will typically be hundreds of toolchains, many missing, lots of build scripts missing or wrong, etc.