I've tried tea tree oil, it was simply mitigating, not enough. OTC antifungals, ditto, mitigation, not a cure. Vinegar, baking soda. ditto.
Fungal infections infect the toenail entirely, so topical stuff that doesn't soak into the toenail sufficently and kill fungus sufficiently doesn't work.
A doctor told me once the way to deal with it is to get a prescription topical antifungal, that these are stronger and better at soaking into the toenail itself. That'd probably be what to try next, if you're afraid of the consequences of oral medication which requires multiple doctor visits to test and make sure you're not harmed by it internally, and that's understandably a concern.