After Alexandre Prokoudine's insistent demand! :-)
I am still not sure how wise this is, since this should be really
considered a "developer-only" option. Basically these tools are really
too buggy and unstable and we should not shine too much light on these.
The counter-argument is that doing so will favor the bitrot.

Well ok. At least let's add a big warning message at the top of the
Playground page, to make it very clear (if that were not already the
case) that basically this is not to be considered a secret feature, but
really more a "we are looking for contributors" option.