_Someone_ at $LARGE_CORPORATION told you to migrate, but clearly this team didn't. They have no idea who you are, what you're working on, what your timelines are, what the priority of this work is relative to other things happening at the company, or whether there's other things you can be doing in the meantime. Yet they actually did some diligence, got it approved (after 2 days even), and got it on their roadmap. As others have mentioned, you need to invest in figuring out how to get things done at $LARGE_CORPORATION. Acquisitions are a dime a dozen and certainly do not pre-empt things like security or compliance. This could be a great opportunity to dig in and develop a better understanding.
At large companies communication and alignment is generally more difficult to solve than any of the actual technical challenges. You may not like it and choose to leave, but at least try to develop an understanding so you can take that lesson with you.