When is Rick going to publish an Estonia/Latvia/Lithuania Guidebook

This out of date 2018 book covers a then-offered Rick Steves tour and does include Tallinn:

https://store.ricksteves.com/shop/p/st-petersburg-helsinki-tallinn

If and when RS decides to do tours of the Baltic countries. Until then, you'll need to look elsewhere.

Episode 5 of this travel documentary may be useful. It covers Estonia, Latvia, Lithuania and Russia (Kaliningrad Oblast). (from 2007)
Michael Palin's New Europe S01E05
also https://en.wikipedia.org/wiki/Michael_Palin%27s_New_Europe

I use Rough Guide as the main source of travel info on the Baltics, aside from a history book now and then.

I used the DK Eyewitness guide for Estonia, Latvia and Lithuania--it was quite thorough, though I do prefer Rick's guides. I had been to Tallinn before so didn't need it so much for that as for Riga and Vilnius--it was a thick book so I removed the sections I needed. between that and internet research I planned--and enjoyed!!--one of my most favorite trips. If I had more time I would have ventured to other cities in these countries.

Estonia (at least Tallinn) is covered by the Scandinavia guidebook.