It may not be "home grown", depending on how you want to define that term, but it does point to a vector for Intel's business model to be disrupted.
Going to ARM for chip IP, tweaking it, and then going to TSMC or some other manufacturing specialist could steadily eat away at Intel's market share and margins. Apple has now gone this route, Amazon is testing the waters, and other tech giants probably aren't far behind.
Just going to throw out there that Amazon paid more for Annapurna than Apple paid for P.A. Semi. That very well might imply that they have a custom uarch. Homegrown very well might be an apt adjective.
Going to ARM for chip IP, tweaking it, and then going to TSMC or some other manufacturing specialist could steadily eat away at Intel's market share and margins. Apple has now gone this route, Amazon is testing the waters, and other tech giants probably aren't far behind.