Thank you for the fantastic work!
I have noticed however that the Pinout file for the ATtiny828 is missing from GIT or the link is broken :-(
https://github.com/SpenceKonde/ATTinyCore/blob/v2.0.0-devThis-is-the-head-submit-PRs-against-this/avr/extras/ATtiny_828.md
Would it be possible to add it?