In a large bowl, whisk together coconut milk, chia seeds, syrup, and vanilla. Continue whisking until mixture begins to thicken slightly. (It will continue to thicken as it sets and the chia seeds begin to gel.)
Pour into 4 glasses or small mason jars and refrigerate while you make the other layers.
Puree peaches and juice in a blender or food processor until completely smooth. Pour or spoon over chia layer.
Puree raspberries, lime juice, and sweetener (if needed) until completely smooth.
Taste and adjust sweetness as desired.
For best texture, strain the seeds out of the mixture by pressing it through a sieve with a spatula. Discard seeds.
Pour or spoon over peach layer.
Refrigerate at least 20-30 minutes before serving for best results, as chia layer will continue to thicken.
If desired, top with something crunchy, like nuts or granola, before serving.