As others have said, fresh snow gathered away from the road is generally safe to melt and drink without resorting to boiling. Just don't eat the yellow snow.

I would consider building and carrying Monty Alford's YuCan type of survival stove (YuCan comes from Yukon, can and "you can" as in "you can survive"). It's made of two nested cans and heated by three parafin tea light candles. No need to gather wood and all that. It gives off less CO than esbit or alcohol stoves so it's safer to use in a snowcave. You use swizzle sticks to stir the snow gradually and you use the ¼" diameter clear plastic tubing or surgical tubing that you thought was only useful in desert survival to drink directly from the stove while it's still warm and so that you don't have to remove the nested can.

If YuCan, try to get the book Winter Wise by Monty Alford.