In the UK the only supermarket I can find that sells powder (after trying lots) is Sainsbury's.

https://www.sainsburys.co.uk/gol-ui/product/sainsburys-conce...

I asked in Tesco and the young lad who worked there (probably 18-19) had never heard of it.

I still dispense it from a Finish powder bottle I've had for more than a decade.