ESG Infinite has an active content development team that publishes one or two blog posts per month and has a periodic newsletter.
Sustain Analytics has an interesting taxonomy of KPIs and a proprietary ESG ratings system to look up publicly traded companies. Lower risk is good. Severe risk is bad.
Here is a nice video explaining their ratings system.
MSCI has another ESG Ratings System and company lookup tool.
ESG Data Providers
Here are a few ESG data providers, most of which also provide additional complementary services.