The idea that the Scimitar could be captured or otherwise adapted Dominion tech is certainly intriguing. There are obvious commonalities in these John Eaves designs.
However, the main features appear unrelated in terms of the plot. The great wings of the Scimitar are part of a unique weapons system, and thus unlikely to be functionally derived from their similarly drooping and forward-angled Dominion counterparts. And the characteristic Dominion engine nacelles with the glowing bits are missing (although every other Romulan ship actually has engine nacelles, making the Scimitar stand out somewhat from the Romulan norm, too - even the Valdore has cigars with glowing bits to denote classic warp engines).
Admittedly, though, the big nacelle things atop the Scimitar are very similar to the things above and below the big Dominion battleship. We never quite learn where all the weapons fire from the Scimitar is coming from, exactly; perhaps Dominion disruptor systems were indeed adopted or adapted? (Although to be sure, the Dominion uses phased polaron beams which look nothing like the green bolts of the Romulans!)
Timo Saloniemi