Not easy, but easier in my opinion than the multi-year project that OP is planning to undertake.

This architecture is not a MAANG architecture and the fix is unlikely to yield experience that will land you a job at MAANG.

If MAANG is your goal, finding yourself a C-Suite sold on a tech modernization initiative whose hired ex-MAANG throughout their org chart will accelerate your MAANG transition.

If your goal is to learn how to solve business problems for medium-to-large sized non-MAANG companies, this company is probably going to yield good experience.

Two different career tracks.