The purpose of national strategic reserves is to stabilize the economy as well as ensure national security in times of emergency and crisis. It cannot help improve and promote the economy of a country.
To improve the national economy, it is necessary to have appropriate economic and monetary policies, improve infrastructure, and improve people's lives, rather than relying on investing in a type of asset. Look at the economy of El Salvador, their economy is on the brink of default even though they legalized bitcoin and added it to the national reserves since 2021.
Bitcoin cannot help or save any national economy.
I would also guess that the stronger you become, as in the more you have in your reserves, the easier it is to get even loans, and spend other money, because people know you can cover it or at least some of it. Look at USA, they do have a strategic reserve, but even if they sell all of it, today, at market price, they still wouldn't cover half of their debt. That is proof that you do not need that much, you just need "some".
And bitcoin investment is great when it comes to this, because it allows you to basically grow with bitcoin price growing. They just need to make sure they do not make the same mistake that El Salvador did, which was buying at the top, they need to wait it out and buy when the bear comes next year.