stainless steel might be less bad for environment if u chuck it in the bin but if you look at the entire process from getting ores to having the steel item i dont really think its a very big difference.

used to live nexto a huge steel refinery and many mental diseases and cancers in the area are up more than 50% not to mention lots of birth defects etc.

maybe its effects are more local idk. Not sure how glass and ceramic are made.

ofc not bad to try and eliminate plastics but having 1 plastic free device that is overly expensive is really just a status thing. it contributes nexto nothing to environmental goals which i think eliminating plastics belongs to.

u can just put the grounds in a cup and pour hot water on it afterall. tastes fine.