If your trying tor recreate the entire drink I’d get the kerns guava nectar because it’s the least gritty and in my opinion the best tasting. You may also have great luck with guava paste! You’re also gonna need some pineapple juice and a little bit of grated ginger (like the tiniest amount, it’s pretty powerful stuff) to replicate the pineapple ginger syrup. You can also experiment with making your own pineapple ginger syrup by placing pineapple juice, ginger slices and sugar into a pot and making a reduction that you can add to your coconut milk and guava mixture.

I think they use to have a guava Tampico.

You can buy guava nectar- I would do that and try different brands until you find one you like