My apologies, I forgot to mention it is a Pi3B board. Thanks for the resource links, I’ll give them a read.
The primary issue with the Blinka library is that instead of you setting the board type, it auto-detects it, and the way it does so shows the board as “Generic Linux PC”, which is not supported by the library.
It’s not a huge deal, as I’ll just add a rapbian container and implement it that way, but not sure which of the balenalib docker images contains python 3 as they are not tags as such. Again not a big deal, I’ll just upgrade from the Dockerfile, but better not to have to, and the fact that Python 2.7 is now EOL.