That's what SNPs are. Specifically, point mutations that are associated with known outcomes (ie diseases) or with group differences.

Point mutations occurring outside SNPs are almost by definition not yet useful. If we know what the gene does or is related to, it's an SNP.

You second paragraph is wrong. SNPs are interesting because they exist in a significant part of the population.

But a new mutation never reported before can as dangerous as you want. A case we found: a woman already developed an illness in her adult life, lets supose it was renal failure. We suspected a genetic root, so we sequenced her exome, founding a never reported mutation that frameshifted a gene previously associated with renal failures. We quickly panel-sequenced her parents and children to check if they had the mutation, which none of them had. So the woman had a de novo mutation in heterozygosis that their little kids were lucky enough to avoid. Imagine the relief. Not useful? I disagree.

but are the ones that are not already in the covered snps interesting ?

23andMe only has an overlap of ~30k with the ~500k (?) ClinVar variants. So less than 10% is covered.