You cannot buy these. You can only buy companies listed in Shanghai and Shenzhen that are enrolled in Stock Connect, which has certain requirements that means these small IPOd companies cannot be enrolled. It is possible that there mutual funds or ETFs in HK that are available, and hold these types of companies.

Me too - these are incredibly interesting companies and the valuations are modest.

Unfortunately as far as I can see it is not possible from where I am (Denmark).

Some Hong Kong shares and linked Shanghai shares are available in interactive brokers but not these ipoes.