Microsoft is also responsible for Go's support on VSCode.
And they just released an Azure Go SDK earlier this year.
Tentacles everywhere.
Both of which make sense, as they're integrations to other Microsoft owned and operated platforms.
How go and lua fit into their product line I'm less sure of.
Look at the number and extent of Microsoft's contributions to OpenBSD, for instance.
Nothing necessarily surprising about this. Yes Go is made by Google, but not by all of Google, just like this project isn't necessarily a first-class Microsoft project (although it might be). And Microsoft has contributed significant amounts of open source in the past few years. Lua is also a great language to support first-class, as its popularity is increasing more each year due to its ease of embedding.