Noone here is planning to inject hydrogen into existing pipelines.

Ok. Not you. But lots of people elsewhere in this thread.

If anything, synthesising methane during the transition so that consumers only have to switch their burners once, from nat gas to hydrogen, and not first to nat gas + more hydrogen and then to pure hydrogen.

Agree. Burning hydrogen has to be done carefully to avoid NOx and other side effects.

And that's not even clear yet, hydrogen pipes will even be a thing for private consumers.

Agreed.

Industrial green hydrogen is a necessity to remove fossil fuels. Residential hydrogen I am very sceptical about. Even 100% clean fuel cells burn too hot for domestic heating.