Observation from german companies (smaller eg 250 employees, mid, big): Azure DevOps is used. Noone uses GitHub. I am sure it's widespread, but rather for small companies
The problem is that Microsoft still hasn't said that officially and directly out loud despite the writing on the wall. They continue to sell DevOps to new teams and point to its "active roadmap" (despite it being mostly unambitious and increasingly "copy X from GitHub"). So a lot of companies still have just enough doubt in the message that DevOps is legacy/dead that they keep inside it and don't migrate to GitHub, because Microsoft keeps giving them that doubt. I'm not sure if it is superstition on Microsoft's part to not kill DevOps (it is an ancient team with quite a legacy; it's maybe Microsoft's albatross), some sort of "magic" migration strategy they want to keep secret until complete, or just that Microsoft loves telling customers what they want to hear and enough companies want to hear "DevOps is alive and in good health" for a number of sunk cost or emotional support reasons.
Once Microsoft learned that ADO was not, indeed, dead, they began to reformulate the path forward for ADO and have actually released a fair amount of preview and release features since the pivot back.
Enterprises like ADO and even when ADO was “legacy”, MSFT continued to see an uptick in adoption. ADO has better integration with Azure, at least for the web app space I play in.