Sorry, please disregard what I said above. I didn’t know that Lakka already had the Python3 package. Currently, it seems to build Python2 for the host and target, and Python3 just for the host. Again, if you want Python 3 to be available on your target, you would have to add it somewhere, either as a dependency of another package, or if it’s not logically a dependency, as a plain addon package in the options file I mentioned above.
To log the build output you could use:
DISTRO=Lakka [...] make image | tee log.txt
In general, if you don’t understand what triggers a package to be built, open a terminal in the packages directory (Lakka/packages) and issue the following command:
grep -rnw -e 'packagename'
This will show you a list of all packages that trigger this package to be built (look for the lines starting with PGK_DEPENDS_). For example, the Samba package, which is part of Lakka, triggers Python 2 to be built. You’ll also see that currently, Python3 is built for the host only, this is because currently no other package needs it to be present on the target machine.
Hint: If a package has no machine target after its name, it defaults to target (“Python3:target” and just “Python3” are equivalent).