Missing import/export fucntion for well known recipe formats

Is your feature request related to a problem? Please describe.

I have quite a collection of recipes managed with Gourmand (ex Gourmet) which I would like to switch to Nextcloud's cookbook app. But as long as there is no genuine import nor export function, there is a risk of a vendor lock-in for normal users by managing recipes in Nextcloud.

Describe the solution you'd like

In Gourmand I can (as I wish) import from or export to my recipes in the following formats:

• Gourmet XML
• Mastercook XML
• Mastercook Text
• MealMaster
• Plain Text
• KRecipe XML
• MyCookBook (MCB)

All these formats have a more or less structured data and have their place in the world of gourmets. I'd like to be able to import my existing recipes from some of these formats into Nextcloud's cookbook app. And when I get tired of using Nextcloud's cookbook app, I'd like to have an exit option (a.k.a. export function).

Describe alternatives you've considered

Sticking to Gourmand and not using Nextcloud's cookbook app at all, while syncing Gourmand's database with the Nextcloud desktop client as is.

Start by reviewing the cookbook app's current recipe data and comparing it with the listed Gourmand formats: Gourmet XML, Mastercook XML and Text, MealMaster, Plain Text, KRecipe XML, and MyCookBook. Define which formats are supported first and what imported and exported recipe data must preserve; done means users can move recipes into and out of the app without vendor lock-in.