I wonder why a country would choose Bitcoin as legal tender when better, faster, more environmentally friendly cryptos exist (ones which can feasibly be used to transact money in real-time, for instance).
You can then use other layers for much faster and cheaper transactions while keeping the base layer as is (as lightning network on BTC and zk-rollups on ETH are doing, or even centralized layers like Paypal/Visa, etc).
They are planning to use Bitcoin Lightning Network which is environmentally friendly and offers instant and almost feeless payments.
Acceptance decides viability of currency. Nothing else really matters.