Regarding preserving food for room temperature storage, I believe it depends on the acidity of the food. If I remember correctly, tomatoes are borderline pH for boiling water canning, so some people add lemon juice if they don’t have a pressure cooker. I think I remember beans being used as an example of a food that MUST be canned at higher temperatures (achieved by pressure canning) Due to low acidity/high pH. I think there was a helpful USA federal government website about it but I don’t know if i would still trust it