I think they are similar to Danvantari, the Ashwini Kumaras, Garuda, the Nandi and so forth. They are not Brahman but worshiped by many people for specific reasons such as personal health and welfare and give out results.
^ This. I equate Medicine Buddha with Dhanvantari. Manjushri is the consort of Saraswati in Tibetan Buddhism.
I wonder if Dasamahavidyas also belong to this category. I have not seen anyone describe the Mahavidyas as 'Shakti' or 'Parvathi' but they are worshiped specifically for certain spiritual goals guided by a trained astrologer/pundit.
There is a difference between Tārā of the Mahavidyas and Tārā of Buddhism. Though Tārā is said to have been "adopted" from Durga. There is a gayatri to Tārā, but I believe it invokes Her fierce form, which Green Tārā and White Tārā do not have; I'm not sure about the other forms of (Buddhist) Tārā:
Om Tārāyai cha vidhmahe
Mahograyai cha dhimahe
Tanno Devi prachodyat
I think it means "Let us meditate on Tārā. May that great and fierce form of Devi inspire and illumine our mind and understanding". If it invoke Tārā of the Mahavidyas I'm not sure I would want to use this without proper transmission or diksha.