The issue with the standard dominance metric is that:
That said, you might be interested in this site which compares Bitcoin to other tokens with a fair launch and distribution:
If you include Ethereum, Bitcoin's dominance is ~66%. This may not be terribly representative of "true" dominance because Ethereum had a ~50-60% pre-mine and also has ~10% of its supply locked up in the deposit contract.
Bitcoin dominance among the pure PoW coins with no pre-mine is ~95%. If you believe (as I do) that PoS is fundamentally broken and cannot last long-term, then this is the metric to pay attention to.