https://www.dvgw.de/english-pages/dvgw/news/germanys-gas-pip...: “The steel pipelines installed in the German gas grid are suitable for transporting hydrogen. They were found to possess no differences in terms of their basic suitability for transporting hydrogen compared to natural gas. Both operational ageing and the required fracture toughness and strength meet the expectations for safe availability spanning decades.”

I guess the last mile is a more difficult problem, but the OP didn’t claim that was solved, saying: “For the moment only at the industrial scale. Home devices are not yet adapted.”