Projects I work on are cross-platform. When evaluating or comparing CI solutions, is that not a requirement to consider? And I'm not saying that not supporting

Projects I work on are cross-platform. When evaluating or comparing CI solutions, is that not a requirement to consider? And I'm not saying that not supporting yet is a problem, but the docs saying "everything happens in Docker" implies a lack of forward-thinking in the design of the system that wholly excludes working elsewhere (including FreeBSD or other FOSS platforms). Apparently it is being supported, but the docs will need some clarification now that some of the advertised assumptions are no longer going to be true.