Remove Last: this isn't great. A selectable list with Edit and Delete buttons is more usable and standard. I saw all those Remove Last buttons throughout the Settings, and it's not much better than Remove All if you have to delete every entry after the faulty one to fix your list. There's plenty of settings that have a dozen items in the list that would all have to be re-entered manually as text.

Dropdowns pre-validate input. Making a box that you can put random additional arguments into means you have to chop up the input in arguments to validate, or maybe you aren't validating it until you press Save, in which case you're making it even tougher to validate the entire file. You can only show items in the dropdown that are valid for that input. Several pages of docker virtual interfaces and named networks is probably not what you want in the dropdown. Eth0 is not a standard interface name anymore in most distros.

That bulk-editing workflow; so I pick items on one page, why would I expect that they'd be carried over when I go to a completely different page in another section of the application? And in that section, there's nothing to indicate that clicking on the gray bar in the middle of the warning text orange box would pop up the list of devices so I can do things with them. What I typically see in things like this is checkboxable list items and a toolbar or menu at the top of the list on the Devices page to perform actions.