I'm Joe Bradford, a scholar of Islamic finance and an advisor. Bitcoin and other cryptocurrencies are permissible to purchase as long as they meet a few basic stipulations: the use case that they were created for is permissible, they act as a store of value, and they are a medium of exchange.
While most cryptocurrencies will fulfill the last two stipulations there are some like meme coins etc that don't have actual use cases and no real utility other than being used for manipulation and pump and dumps. Those coins should be avoided outright.
for more information on the topic you can check out my website where I have several articles and videos about the topic or schedule a call with me to discuss any intricacies about a coin you are looking to purchase.