I doubt any country would accumulate and hold bitcoin for a long time. They would rather develop their own digital currency and that's what we are seeing now from countries like China. They even made a proposal recently to issue a regional stable coin that will be backed by four major currencies in Asia.
For Iran's case, they are already taxing the miners. That's probably better than getting involved with bitcoin.
For North Korea, they are reportedly connected with hackers attacking crypto exchanges. I don't think they want to declare they own bitcoins.
It's hard to say they are holding because as a government, they should be transparent on how they will manage the wealth of the nation.
Also, it's kinda odd that a government who like a centralized policy investing in a decentralized system, if they would like bitcoin to be a success in the future, then they should be legalizing everything to give way on improvement of the adoption process.
Bitcoin has always been an speculative asset, being a store of value is sometimes makes people doubtful due to its price volatility.
I bet there are government controlled banks who are already buying and selling bitcoin. They don't have to use bitcoin as a currency but they can still invest in it the same way they use depositor's funds to invest in real properties and stock market.