I would investigate before undertaking any treatment, either conventional or alternative, no matter how great it sounds.

https://pubmed.ncbi.nlm.nih.gov/20196932/

Some of the articles on PubMed are good, but are all of them good, that is, truthful? Consider that FDA and other 3 letter agencies do not want folks to use alternatives, especially something that grows naturally. An apricot pit is probably a lot cheaper than a chemo session. Just sayin'
BTW, my boss 'cured' his niece with a protocol using arsenic, when she was dying.
I don't have any data on this - but supposedly many drugs could be fatal if taken in high enough doses.
Interesting about cyanide and B12 vitamins:
"However, each (VB2) have a different molecule attached to the cobalt ion. While methylcobalamin contains a methyl group, cyanocobalamin contains a cyanide molecule."
https://www.healthline.com/nutrition/methylcobalamin-vs-cyanocobalamin#conversion
The article suggests that cyanocobalamin is a little bit better than the natural form.

I understand what you are saying and agree with your analysis. My main point was to suggest people investigate and work with someone who has experience to avoid any potential harm.