I accidentally got a cut in on the webbing of my thumb (just the skin, not tendons are anything). This is very stretchy skin that moves quite a bit and so it's healing very slowly. Unfortunately "Don't use my dominant hand" isn't an option. Are there any other things I can do to help speed up the healing process?
If it's a small cut in the webbing the most important thing is, to keep the wound moist and pliable, so the stretching doesn't crack it open all the time. This is what keeps the wound from healing properly. Also you want to keep any infection at bay as this slows healing and is also plain annoying at a place like that.
The best solution I know of isn't really a life hack but plain antiseptic first aid cream. This will tick both boxes. You want to use lots of it and regularly: you never want to allow the wound to dry out.
For the first days, if your work allows it, you may want to wear a simple bandage and wound pad, as plasters are impractical at this place. This will hold the cream in place, prevent further drying out and protect from dirt. So you won't have to remember to apply cream all the time and you won't get any cream on everything you grab.
Wear gloves for washing dishes etc. For heavy manual labour wrap electric insulation tape over the bandage and wear gloves.
At night you want to take the bandage off to allow air to the wound. The cream should keep the wound sufficiently moist until morning. If it doesn't, just keep the bandage over night.
Do all this while the wound is wetting, but stop once it is closed over.
However if the skin is gaping open when you stretch it, you should have a doctor stitch you up.