Hey, you are right, there should be a packaging, or integration into
pd-extended - but actually, i am not currently maintaining my externals at all because of a serious lack of time. They "just work" (or they don't).
I have tried for years, but no one seems interested in volunteering to
package or integrate flext and flext-based externals (xsample, py, dyn~, pool, fsplay~, clk, zeroconf and many others) for more general use.
FWIW, flext lib and a few externals are a part of auto-building script in pd-l2ork.