There is currently no plastic suitable for home composting. There is no standard for this and it would be difficult to create one because composting has to be carefully managed, in order to create and maintain the conditions prescribed. It would also be unlikely that many home composters would even read the standard. The result would be that fragments of plastic will remain in the compost.
Plastic marketed as ‘compostable’ has to comply with EN13432 which requires it to convert into CO2 gas within 180 days. This can only be achieved in industrial composting units (it is not achievable in home composting, as it requires sustained high temperatures) but even then it does not make compost or anything useful for the soil. Instead it makes Carbon Dioxide which is a powerful greenhouse gas.
According to a Jay Sinha and Chantal Plamondon in their 2017 book ‘Life Without Plastic’ “To be called a bioplastic, a material only needs 20 percent of renewable material; the other 80 percent could be fossil fuel-based plastic resins and synthetic additives.”
Even when “compostable” plastic is introduced into industrial composting, the results are not satisfactory.