that is a deep question, the only advice I could offer is perusal of Recognizing Reality
by Georges Dreyfus:
Dreyfus examines the central ideas of Dharmakirti, one of the most important Indian Buddhist philosophers, and their reception among Tibetan thinkers. During the golden age of ancient Indian civilization, Dharmakirti articulated and defended Buddhist philosophical principles. He did so more systematically than anyone before his time (the seventh century CE) and was followed by a rich tradition of profound thinkers in India and Tibet. This work presents a detailed picture of this Buddhist tradition and its relevance to the history of human ideas. Its perspective is mostly philosophical, but it also uses historical considerations as they relate to the evolution of ideas.
As a general observation on your question, the notion of 'ultimate phenomena' is self-contradictory, because 'phenomena' by definition are 'that which is to be explained'.
I think it is also a bit misleading to think of the Buddhist view of 'dharmas' as 'ultimate particles' insofar as these are of momentary duration
, that is, they come into and pass out of existence continually. They are not like the 'ultimate particles' of atomism, which persist in time.
As to the status of concepts in Buddhist philosophy generally, Dreyfus' book considers that question here
Learn to do good, refrain from evil, purify the mind ~ this is the teaching of the Buddhas