in general you can suggest feature requests to either one of the development mailinglists (gnupg-devel@ oder gpg4win-devel@) or directly on dev.gnupg.org. Please describe your usecase in good detail, especially why it is an improvement over other possibilities.
Note there is already a blog post about using TPMs on GNU/Linux systems, maybe the work is needed to find out how to do this on Windows operating systems as well:
(In general: work is done if somebody does it and convinces the developers to add this to the GnuPG core. Which means making the contribution easy to pick up and maintain, among other things.)
Thanks for the suggestion and
Best Regards,
Bernhard