Is there any software currently that can trunk-track and decode a DMR Motorola Capacity Plus Multi Site (TRBO) with an RTL-SDR?
DSDPlus can. IMO it's the best option.
DSDPlus – Digital Decoder . that's the free version, many years old. You have to download both the DLLz zipfile and then the main zipfile. And you have to put them all in a single directory (preferably something like c:\dsdplus). And then you'll have to play around and ask questions to get it all working.
But the Fast Lane versions (avaialable via paypal donation) are much better. Fast Lane is updated fairly often. It requires Windows and a single RTL dongle for full trunking of Cap+, Conn+, NXDN, P25.
Mike