What specific hardware do you have in mind ?

Meantime - if your target is specifically learning/certifications - have you tried the virtual labs?

https://learningnetworkstore.cisco.com/cisco-learning-labs

https://learningnetworkstore.cisco.com/cisco-modeling-labs-p...

They are not “free”, but the pricing does not seem to be too bad if your goal is the certification.

You can also search for “GNS3” and see what pops up :-)

I would argue virtual devices are the most friendly approach e-waste wise.