I’m going to get philosophical here- you think about and do what you can to address safety and you remind yourself that whatever happens, you’ll figure out what to do, just like you’ve done your entire life.
It’s very important to understand and accept that he is losing the ability to reason, to accept reasoning, to be aware of his cognitive decline. If you continue to try to reason with him, you both will be very frustrated.
If he’s unsafe at the stove and determined to cook, be nearby and/or cheerfully offer to cook together, or hide the pots and pans until each time you need them, or unplug it and just decide to use the microwave. If he is leaving the house, buy the little childproof door alarms you place high up and you’ll be alerted. If he’s using power tools, slowly remove them (I put things in my car trunk). He’ll notice things changed or missing, be noncommittal, and he’ll soon be on to something else.
Time to think about home safety- remove throw rugs and move any floor clutter, have brighter light bulbs in the fixtures, install a higher toilet and grab bars (Amazon has nice ones under “decorator grab bars”). If wandering is a concern, make sure his wallet has a card with your full address and your cell number.
Driving is a whole other issue we Connect friends can help with if you need that.
Bottom line- address what you can, hope for the best, and remind yourself often that you have a whole life’s practice in problem-solving and you’ll figure out what to do quickly, if something drastic happens. Then relax, as best you can. You are the key to what is becoming a house of cards, and being less stressed about the “what ifs” will help you think more clearly and deal with what actually does happen.