Clearly I don’t recommend this, but years ago after having an ingrown toenail causing months of pain, I got drunk, decided I’d had enough, and cut a sliver out of it with a breadknife. Ridiculous decision, but cured it forever.
In terms of pain alleviation before surgery (medically trained or otherwise), I can highly recommend stuffing the toenail with tissue paper as close to the ingrown part as possible. Poke it in with a toothpick or something. It acts as a cushion and can train the nail to grow away from the skin.
Unintended bonus of having my own ingrown toenail though: I have always played football and refused to stop even when the pain was at it worst because I love playing it so much. I’m right footed and couldn’t kick the ball with it at all during that time. Instead I forced myself to use my left constantly. I was shocking initially, but weeks later became a two-footed player. Best thing that happened to improve my game long term.
The bread knife was the sharpest object in the flat I was renting at the time. It was also serrated on one side, which proved useful.
Although clearly this kind of operation should only be undertaken by trained bakers.