Can i purchase physical card & top up without China mobile number?

I'm afraid no because you need to upgrade it on the app or WeChat mini program which need a number to register to top up. But you can go to the service center at Dongzhimen to upgrade it.

I think you should be able to get a card from a staff. Beijing authorities made a guidelines in late March of this year to maximise tracking individual identities on transportation in Beijing. Foreigners should be able to get a card or a single ticket with presentation of their passport. In case of refusal, you can try different location in Beijing or even in Tianjin City. City Card of Tianjin with China T Union logo will do the job also.