In the UK, where I live, there are a number of options for dairy-free greek-style yoghurt - for example Alpro and Oatly. It doesn't necessarily need to be one of these brands, so if you have a different brand, go for it! The most important part is that the yoghurt needs to be thick and not super liquid and runny. If you can only find regular vegan yoghurt, you can transfer it into a cheesecloth and hang it over a bowl for an hour, so the excess liquid can drip off and you're left with thick greek-style yoghurt.