Vector.dev does not come with armv6 target, so it cannot be installed to old RPi 1 or RPi Zero. 
However, it can be compiled from source for that CPUJ architecture. I used `arm-unknown-linux-musleabihf`.

I use 0.31.0 version and followed this guide: https://vector.dev/docs/setup/installation/manual/from-source/#docker
Apply the following patch to the codebase, then you'll be able to do `make package-arm-unknown-linux-musleabihf
` to make a tar.gz or `make package-deb-arm-musl` to make a deb package.
Building vector consumes about 10Gb, and 10Gb more to build a deb.

I had to drop kafka support, as librdkafka was very stubborn and wanted to be compiled for armv7 target even when all the components were build for armv6.
I had linking issues concerning vfp3 functions, so I dropped the whole feature as I did not need it. 
I am sure it can be fixed, but the easiest way was to just disable kafka support.