So I have been wondering what if a Government somewhere in the world wants to legalize bitcoin or any other crypto for that matter. How would it work.

First of all the government will be trying to legalize a means of exchange that it neither controls the demand, supply and creation. It can't even be used as a means of effecting economic change like other currencies can be used by controlling money supply and interest rates.
And if we are equating bitcoin to the possession of assets like gold or diamond. They cant even control bitcoin mining, like they issue licenses to mine gold or diamond
So is bitcoin being a legal tender even possible and how would it work.