No mention is ever made of nanomedicine in Star Wars canon. Is it because bacta can accomplish what nanomedicine can accomplish or could the two exist as different procedures?
Bacta is a substitute for almost everything medicinally related in Star Wars
We don't have much information on this since Disney decanonized everything. But we do know the basics.
Bacta was a thick, gelatinous substance with seemingly magical healing properties. It helped the body regrow tissue, including nerves, skin, and muscles.
Due to its 'one-size fits all' use in medical applications, it was a highly prized and commonly used medical treatment for most if not all injuries.
So the answer is "yes", which is helped by the fact nanomedicine is not mentioned in Canon.
We have a tiny bit more information in Legends, but not much.
Bacta was a synthetic chemical substance that consisted of gelatinous, translucent red alazhi and kavam bacterial particles that were mixed within a colorless, viscous fluid known as ambori.
Bacta was invented by the Vratix on the planet Thyferra in antiquity, with the galaxy at large learning of its properties around 4100 BBY.
But even so, it is still described as a miracle fluid that can solve almost every problem..
Bacta was often thought of as a "miracle fluid", and seemed to be effective against almost every type of injury and ailment across an incredible cross-section of species throughout the galaxy. It was considered to be the best medicine available anywhere, replacing the previously-used kolto.
Bacta (Legends) | Wookieepedia
And if we look at Kolto, it's just a Bacta-lite (with no canon counterpart, by the way).
So again, the answer is "yes".
There is nano-tech healing in the Star Wars universe, however it is extremely expensive to make. Bacta, in comparison, grows naturally on the planet Thyferra. This is probably why its the most common - it's cheaper and also very powerful; as it can heal any non fatal injury.
On a side note there is also Kolto which is not really in common use anymore, as Bacta is more powerful. Kolto is harvested from the planet Manaan.