My experience in this space is that I was first employee at Solcast building a live 'nowcast' system for 4+ years (left ~2021) targeting solar radiation and cloud opacity initially, but expanding into all aspects of weather, focusing on the use of the newer generation of satellites, but also heavily using NWP models like ECMWF. Last I knew,nowcasts were made in minutes on a decent size cluster of systems, and has been shown in various studies and comparisons to produce extremely accurate data (This article claims 'the best' without links which is weird..), be interesting on how many TPUsv4 were used to produce these forecasts and how quickly? Solcast used ML as a part of their systems, but when it comes down to it, there is a lot more operationally to producing accurate and reliable forecasts, eg it would be arrogant to say the least to switch from something like ECMWF to this black box anytime soon.
Something I said as just before I left Solcast was that their biggest competition would come from Amazon/Google/Microsoft and not other incumbent weather companies. They have some really smart modelers, but its hard to compete with big tech resources. I believe Amazon has been acquiring power usage IoT related companies over the past few years, I can see AI heavily moving into that space as well.. for better or worse.