To be fair the situation has changed drastically over the past 12 months.

After 2.0, AOT got enabled by default, drastically reducing size, then 4.0 drastically reduced size, then the build-optimizer (default with 5.0) drastically reduced size.

There was no clear way on how to do this if you wanted to use universal though. The CLI never supported it for ages. Does it support it now?

It does, there is a wiki page on it.