Hi Gaurav,
There are two sets of functionality in this module,
1. Users can claim a node, we record in the backend who claimed what.
2. Admin gets emails of any claim.
#1 is a blocker to get the 8.x-dev release out. This is the core logic of the module. You are right that in D7 we have saved data as entities, I would like to keep it same for 8.x as well, feel free to suggest an alternative. It seems D8 has good support for Entity API, many things are in core now.
#2 is more like an alert system built around it. There are a couple of issues pending for 7.x where users have asked to turn off the alert as it spams the admin with emails for large sites. Instead, a simple listing page where admin can see the claims etc seems to be ideal, we can tie this page with permission string and then anyone with permission can view the claims, rather than only limited to admin.
But I would not worry too much about #2 at this point, even the integration with Trigger like you rightly pointed is not applicable for 8.x Maybe we can do Rules instead.
If we can get the main claim logic working, we can quickly consolidate and make a dev release available.
Thanks for helping out again. Let me know if there are any other doubts.
Thanks,
Swarad