The concordes engines produced around 75% of their thrust at M2.2 in the diffusor section and only around 8% came from the actual engine. Another 29% thrust came from the nozzles, whereas the supersonic shocks at the intakes prosuced around 12% drag.
The SR-71 was similar in this respect. At M2, thrust produced came 17% from the compressor, 25% from the reheats, and 58% from the inlets. Essentially, the compressor served to maintain flow through the inlets.