Are biodegradable or compostable poop bags actually better?

It depends on disposal. Specialist-community threads on r/dogs repeatedly point out that many 'biodegradable' bags won't break down in a landfill, and one PSA thread specifically notes Earth Rated bags are recycled-content rather than truly biodegradable. For genuine composting, look for certified home-compostable bags meeting ASTM D6400 and EN 13432 standards, such as the G.A.S. bags highlighted by thesprucepets.com and whole-dog-journal.com.