I don't have any first-hand experience with embedded myself, but I've seen positive comments on different forums about using Nim in production for embedded devices. For example, see a couple pages of comments by girvo [1].

Also there's a video on writing keyboard driver in Nim [2].

[1] - https://hn.algolia.com/?dateRange=all&page=0&prefix=false&qu...

[2] - https://youtu.be/dcHEhO4J29U

You might also find interesting Nim on embedded material on the back-commentary of elcritch (https://news.ycombinator.com/user?id=elcritch ). E.g.: https://news.ycombinator.com/item?id=40964296