From August 1, the law will come into force, but CBDC won't work everywhere and it is not yet clear how this will work in practice.
I do not understand the idea of CBDC. The country does not want bitcoin to be legalized but since they see the people's interest in crypto coins, they decide to launch their own CBDCs. The government control CBDC with no control over the supply is a no threat to bitcoin.
Also when all the countries do not have their CBDC, how will they operate within the countries? One contury want to trade in fiat while other in CBDC

Or will the people be allowed to buy bitcoin through CBDC ?
I don't see this model working well as of the developments till now

The government doesn't want private individuals (corporations) to control a cryptocurrency as it could undermine the national currency control schemes (e.g., avoid sanctions, controls, and legal obligations). As long as the government controls it, it can impose a much broader swath of restrictions, albeit digitally. For example, they don't have to issue sanctions. They can quietly prohibit cryptocurrency exchange by any party that is deemed whatever. Dissidents, thieves, political figures, you name it. They control the entirety of the pocketbook. Credit and debit cards are a highly loose form of this digital control. With CBDC, they can do it instantaneously. You can only spend on what they say you can spend with whoever they say. Don't want anyone buying guns? Ban the exchange addresses of all gun dealers. No legislation or negotiation is needed. This is an autocrat or dictator's dream.