That is how Mono started.
Additionally here is some historical refreshing about two other attempts,
https://www.gnu.org/software/dotgnu
https://www.codeguru.com/dotnet/net-nuts-bolts-the-joy-of-ro...
A surviving clone of the repo is available here,
https://github.com/SSCLI/sscli_20021101
Finally, this doesn't change the fact that the CLR was only yet another version of this idea, there are plenty of others since UNCOL in 1958.