Online casinos can use ISO 27001, this is the requirement for remote gambling businesses that want to get license in certain jurisdiction, I thought you all know that ISO 27001 is already a mandate from gambling commission?
This ISO comes with a penetration test show that demonstrates a vigorous manual assessment of Web applications to make sure that it's secured against fraud and unauthorised access.
I am not sure this will make any difference because I don't hear about online casinos getting hack almost evert month like crypto projects do, so to me it doesn't makes a lot of difference.