Actually Timo, Janeway used a site to site transporter in one of the episodes when Voyager's computer core was stolen.
She explained to Leonardo that the device would be capable of relocating them several kilometers from their then position (which she used it for later in the episode before flying off with Leonardo so Voyager can transport them).
The device was not transported with Janeway and Leonardo to my knowledge.
And Janeway only used the computer core to send out a pulse on a specific frequency so Voyager's transporters can lock onto it and beam it back on board.
So ... what we do know is that site to site transporters of 24th century era are capable of beaming one or two individuals from one site to another, and that they are light/portable, but do not transport themselves (at least not from on screen evidence).
As for the future, I would not be surprised to discover Starfleet managed to miniaturize such technologies and add better functionality/capability in them.
Nemesis happened only 2 years after Voyager got back, but the site to site transporter could have been introduced a decade before Voyager was launched or earlier (we don't know when exactly it was introduced).
Voyager could have been using the most used version of the device, but the Enterprise being the flagship and all, not to mention various info Voyager brought back, and Data being adept at science ... it is possible he could have made a device capable of transporting a single individual to a specific destination.
It's possible the pin device was only working as a half-tranporter which needed an environment with technology capable of finishing the transport which the device itself began.
I dunno, it's merely speculation, but if Data was behind the creation of the said device, he could have used his expertise to develop an early prototype.