If the game owner is a Pro user, you could use jakob's PublicSheet script. This creates a read-only duplicate of character sheets, and you can whitelist certain attributes (like, say, hit points) so that they can be edited. In practice though, if its a game like D&D, this will probably create more hassle for the players than it's worth, as players using their sheets will need to adjust spell slots, inventory, etc. But if its a game with relatively simple stats, it could be a perfect solution.