Tõnis keeps himself busy as a freelance-GIS-person under the name LonLat OÜ. Most often you’ll find him offering services under the auspices of UEC OÜ to bring you spatial awareness in IT consultancy.
Tõnis is an OSGeo Charter Member and has helped co-organize FOSS4G conferences over the last years. He tries to do some writing up on the things he is doing with (mainly) FOSS4G software on his website: https://tkardi.ee/writeup/post/ in the hope it’ll be useful.