It looks that the code for Inventorian also works for tdBag2. I have changed line 537 in peddler.lua in elseif IsAddOnLoaded("Inventorian") or IsAddOnLoaded("tdBag2") then
and i see the coins.
It would be nice if the addon would get an update for this on CurseForge/WoWInterface.

Edit1: Looks like there's still a little problem. The coin icons are sometimes shifted arbitrarily. See attachment.

Edit2 (sorry): It seems another addon is responsible for the problem in Edit1. Is Worthless (https://www.curseforge.com/wow/addons/worthless) disabled the problem is gone. Worthless itself has the same symptoms with shifted marker. It must be an other addon or tdBag2 respectively peddler itself. I will look into it further.

Hi old chap!

I'll see if I can get some time soon (perhaps over the weekend) to look into adding tdBag2 support. Maybe as a first version we can live with the peculiar movin' coins at times - does it seemingly refresh itself correctly when moving an item to another slot?

does` it seemingly refresh itself correctly when moving an item to another slot?

Yes, and also if you flagged/unflagged any item