This is very old news. Hot paper cups with compostable film inner linings have existed for years and on widely for sale in the UK and North America. Suppliers like International Paper, Solo, Stalkmarket-Planet+, Vegware, etc., have all sold and distributed non petroleum compostable plant film lined hot cups for a long time.
And they are all certified compostable by 3rd party testing organizations... This is real old news and millions of compostable cups are already being sold and marketed globally.