A great read+great magazine.
TL;DR: Old bikes last way longer than new bikes. From a production standpoint, steel bikes have a smaller carbon footprint than aluminum or carbon frame bikes. Conventional bikes use fewer consumables over their usable life than electric bikes. Among electric bikes, cargo bikes use the most resources to run and maintain.
In combination with old bikes, we have e-bike conversion kits. You can get a kit from companies like Cytronex or Bafang with a motor, battery, and battery management system that all attach to the frame and are wired up with a control knob on the handlebars, making a very inexpensive custom ebike. If the system fails for whatever reason and you can’t fix it, you can just take everything off and it becomes a normal lightweight bicycle again, but the modularity of it makes it much more fixable and tunable than most bikes that are electric from the factory.
My cousin, who works at a bike shop says that those things are super dangerous and break easily. Is this true in your experience?