It's actually the US that followed the footsteps of other countries as far as Bitcoin is concerned. As to which country would follow the US, there's a number of countries that have shown interest.
The Czech National Bank, for example, has mentioned that it considers having a portion of its Euro reserve in Bitcoin. There are also countries like Argentina, Japan, Brazil, and others where bills for a Bitcoin strategic reserve are filed.
Belarus has also considered going into Bitcoin mining to accumulate Bitcoin reserve. Even Russia could get into the game.
The USA strategic reserve is from seized bitcoin and there is no plan, at least now, of purchasing more bitcoin from national reserved money.
There's no plan to directly purchase Bitcoin, but there various plans on how to accumulate Bitcoin without using taxpayers' money aside from keeping seized coins.
There's even the proposal to swap a portion of the country's gold reserve with Bitcoin. It's also an option to accept Bitcoin payments for tariffs, taxes, and so on.
Or there's what Bhutan is doing, state-owned Bitcoin mining. Or perhaps El Salvador's Bitcoin bond.