There's a merged pull request on the void-packages repository

common/profiles: introduce XBPS_{,TARGET_}WORDSIZE
https://github.com/void-linux/void-packages/pull/13330
Description: The host and target word size can be used to determine whether cross compiling certain packages is possible.
One example is qt5 webengine which can be built for e.g. armv7l iff the host environment is 32 bit also.

N.B. for armv6l* cross compiling fails anyway because of missing neon support for some part of webengine.