Welcome to GoY Beigeandco, where do you live on the planet and would it be possible to add a photo of the rockery to your question please.

Dry shady rockery eh? Moongrower is the person to help but it sounds very tricky!

That's why I need to know where the person skiing the question lives... and a photo is worth hundreds of words.

Good old London Pride will grow anywhere. (Saxifragia x urbium)I have some spreading well in permanent deep shade under a large Mahonia. It has sprays of small dainty flowers but is not showy. Have a look at Long Acre Plants on google. They specialise in plants fr shade and have a range of perennial geraniums some of which might be useful to you. There area a few ferns that are happy in dry shade- sadly there aren't many bright flowers for that situation .

Brunnera 'jack frost' would be fine, also Buglossoides purpurea is happy in dry shade.

It all depends were the person asking the question is. If they want actual rock garden plants I wouldn't suggest those Stera and Sheila are.. but I won't make any suggestions until Beigeandco tell me where he/she is a, preferably, puts up photo.