@nprofile1q... Me, too, think adding overlays configs into `poudriere jail` is straightforward.
Needed time to find that `poudriere ports` to create optional ports tree for overlays and specify them (as needed) on `poudriere bulk` with options.
And I think overlay itself is currently poorly documented.
More, using overlays both on poudriere and bare-metal requires special care.
I've documented it here. (Not official, though.)
https://brew.bsd.cafe/TomAoki/Tips-and-Tricks/src/branch/main/poudriere/README.mdWas hard to determine the conditional that works reliably.
Maybe allow specifying overlays via /etc/make.conf would be straightforward, too.