Plastic is safe (for your plants, not for the oceans): plastic is an organic polymers, so molecules are much larger than roots can absorb, and the elements are usually just normal organic components. The danger for ocean is just the size: too large (also in case of micro plastic) and they tend not to decompose (also in stomach).
But I would check pots for plants (and possibly for vegetables): colours (pigments) may contains some heavy metal (which gives the colour). Plant pots tend to mantain the colour, so they are safe. Other plastic recipients tend to lose colours.
In any case, most of recipients (also clay) should work well. Check that they have natural colours and more traditional forms (the others could have more dangerous materials, especially for "artistic" pots). Choose material that will endure (so less "emission" of material).
Soils contains also metals, and small quantities are not dangerous (in effect we need some of them). I would assume you will not eat only from the plants on your pot, and probably your soil would be much better (more organic, so few metals).
Glasses are also good materials and inert (so glass will not release substances, and on the other hand, glass should not have dangerous elements). Plant on glasses are also nice to see, but you should care that the root will not overheat, and there is not extra greenhouse effect.