As for house rule, why not water tossed in face, strong scent placed under nose, or even shaking the target? This shouldn’t revive all types of unconsciousness. I wouldn’t permit someone shaking someone out of a coma.
There should be a reasonable distinction between unconscious and comatose. My rule would be along the lines of ‘much harder to waken during combat’ though I’d probably give a small chance based on time spent. Once, combat is over, my personable preference would be that most unconscious effects should have a realistic duration. Simple unconsciousness lasting a few minutes if no strong reason for longer.
My view being just because we have magical means of dealing with some issue doesn’t mean standard real-world solutions can never work.
Sam inspired me to consider that this sort of house rule could have its own drawbacks. If you feel the need to encourage ‘proper healing’ or group usefulness, or purchasing of potions, you could have lingering negative consequences for not using standard practice (whatever standard practices you determine). For instance, if revived by water/shaking/salts/etcetera the player could be groggy. Could be slightly more likely to miss. Could get dizzy spells or fits of vomiting.
The key for me is to have some options so that play doesn’t come to a full stop.