> they abandoned that approach in WSL 2 because, among other reasons, it was just too much work to achieve Linux compatibility

Any particular citation for this claim? I tried to do some searching and couldn't find anything definitive, but my memory from contemporaneous conversations and articles suggests that the primary reason was really performance, since the differences in how filesystem access in particular work between Windows/Linux were such that some of the I/O bottlenecks were deemed too difficult to impossible to address.

Certainly WSL2 has higher compatibility, but I'm not sure that compatibility and not performance was the primary driver, and would love a source if you have one.

Relatedly, it's worth noting that a number of other platforms have developed and shipped syscall translation layers for Linux binaries, including FreeBSD and SmartOS/illumos.