I've found something far more concerning than lounge access:
"Air transit/transfer services at Hong Kong International Airport (HKIA) have resumed gradually. From 15 June 2020, passengers can use HKIA for transit/transfer on flights operated by different airlines under the same air ticket, provided that the passengers have checked through at the origin port with their boarding passes printed and baggage tagged-through to the final destination. Passengers should also confirm in advance that they are able to enter the final destination. Please check with airlines for details. However, transit/transfer services at HKIA to and from all Mainland China destinations are currently not available."

I'm coming from Taiwan on a different airline / different ticket. Does this mean I won't be allowed land side to check my luggage in for my BA flight? Eeeek