Is there a way to implement a marker of some kind on the app and website to indicate species you have seen when in Observations.
Hi, welcome to the iNat Forum! On the website you could add tags to your lifer observations, like this:
There’s a feature request for adding some sort of marker / icon to lifer observations here: https://forum.inaturalist.org/t/add-icon-to-observation-when-its-a-new-species-for-me/51910
Did you notice this thread?
https://forum.inaturalist.org/t/my-latest-new-species/73427
Have a look at this nice little app:
https://glauberramos.github.io/inat/
Here you can draw a list along your Timeline.