BNO visa and crypto CGT

I am Hong Kong local, a personal crypto trader and currently planning to apply BNO visa. I would like to liquidate all my crypto holdings right before I entered UK so that I would not have to pay CGT upon arrival. Could the selling be done through fiat pair (BTC/USD) of the crypto exchange (which is KYCed using my HK identity) and without being withdraw from exchange to my own bank account? So that upon arrival using my approved BNO visa, I could buy back the crypto easier without sending fiat from bank to exchange again. Also I would like to know from which dates do I need to keep my transaction records on the exchanges for better preparation for tax report once I become tax resident using BNO visa.

Hi

We cannot advise you on how to liquidate your assets.  
If you liquidate your assets before ariving in the UK, you would be liable for capital gains in Hong Kong, subject to their tax laws.  
When you arrive in the UK, you would need to review the guidance on residence, to determine whether you would need to include the disposals in a tax return.  
Please have a look at the gudiance at RDR3 (RDR3 Statutory Residence Test).

Thank you