Major-ish. It was getting experimental module support around 2018; arguably go get was already better than Python's mess, but it wasn't great. It wasn't that widespread in industry yet - we could very rarely hire anyone with a Go background at that point.

Pretty major. I started using Go in like 2009 or 2010 and industry adoption was already pretty wide in the mid 2010s (largely replacing Java moreso than Python, IMO).