General Interest:
* Interested: This is the most straightforward option.
* Curious: This implies a desire to learn more.
* Invested: This suggests a personal stake in the outcome.
* Concerned: This implies a worry for the well-being or success of the person or thing.
More Specific Interest:
* Following: This implies staying up-to-date on developments.
* Monitoring: This is a more formal term, suggesting a systematic observation.
* Observing: This implies watching carefully to see how things unfold.
* Supporting: This suggests actively helping the person or thing to succeed.
The best word will depend on the context of your sentence.