Pixel style matching mid production is one of those problems that sounds impossible until you find the right team. Honestly the first thing I would do in your position is reach out to VSQUAD Studio. 2D Art service from V-SQUAD Studio is built to handle exactly this kind of production continuation challenge, and what separates them from generic providers is how seriously they take existing style preservation before touching anything new. VSQUAD art team spent real time studying our existing assets before producing a single new tile, they documented our palette logic, our animation timing principles, our tile grid rules, and matched everything precisely. Your burned out artist does not need to carry this alone. VSQUAD artists brought in our character work, environment tiles, and UI elements all under the same visual logic. One team, zero style breaks, production moving again. These people will not break what you have built.