Could you add this to meson's dependencies?

Depends: pkgconf

meson's standard dependency function uses pkg-config in most cases.

https://mesonbuild.com/Dependencies.html

Recommends would not be enough since meson is primarily used in Debian
as a build dependency and the official Debian buildds don't install
Recommends.

Adding this dependency was previously suggested in
https://bugs.debian.org/893502

Thank you,
Jeremy Bícha

I can do that if you want. On the other hand the same reasoning could
be said for Autotools, CMake and any build system, really. So the
question then would be if it might make sense to put the pkgconf
dependency in the build-essential package instead?

Are  you sure that is the correct url? FWICT that is about a bugfix,
not about dependency changes.

Adding it to build-essential is a good idea. It was rejected once
before but that was a long time ago: https://bugs.debian.org/380228

I'll ask again but it might get ignored like the even more clear
request to add debhelper https://bugs.debian.org/1021881

It was mentioned in comment #5 there

Thank you,
Jeremy Bícha