Yes, Findings 1 is compatible with macOS Sierra, no worry.
Also, note that when you start Findings 2, all your Findings 1 content will be there already. Then, ven after you use Findings 2, you can still go back to Findings 1 and find all the changes there (except for things dependent on new Findings 2 features, like collections). Note that it’s best to not run both versions at the same time on the same machine (because they still share some preferences, so it could trigger some weird behaviors).
You can also read more about it here: Transferring data from Findings1 to Findings2
Finally, have a look at this topic: What is new in Findings 2, compared to Findings 1?
Let me know if you have more questions!