24Pcs RJ45 Port Lock RJ45 Port/Dust Blocker RJ45 Dust Cover Cap Ethernet LAN Hub Anti Dust Cover Plug Cap Blockout Protector with 2 Removal Keys Red

Absolutely. For testing purposes, I put my ONU stick in an SFP+ port on my 24-port Dell switch and plugged my laptop into one of the 1GbE ports. It picked up the public IP just like a router would. I recommend getting something like https://www.amazon.com/dp/B07C6GKQ5L/ to plug the other ports. It'll keep random crap out, and should at least slow down anyone trying to plug something in. If you need to be a little more persistent, https://www.amazon.com/dp/B0DKHCX674/ is a hard plastic version that requires a special key to remove. As others have said, a simple media converter would work just as well for this task, but if you already have a switch you're not using, and it meets all your requirements, you might as well use it.