Got a refurbished Alexa device from Amazon, it was shipped in a different package but the condition was new. No signs of usage. Still works fine to this day after 3years.
Just an additional note here. Refurbished Alexa Devices, Kindles, Firesticks are "Amazon Certified Refurbished". These are safe to buy and come in a plain Amazon packaging. They carry full manufacturer warranty from Amazon as well. I myself bought a refurbished Kindle recently and it was basically a brand new unit in a plain brown box.
Most other refurbished items are sold by third party sellers. These only carry 6 month seller warranty and could be sold as refurbished due to being a customer return, damaged packaging, cosmetic issues or maybe even repaired. You may or may not be able to use the invoice to claim manufacturer warranty.
My friend bought a refurbished Zephyrus 16 for 1.6L. The only issue was a very tiny dent on the lid that can only be seen at an angle. We were able to register for the full manufacturer warranty using the invoice and recently got it extended too. Before purchasing, I made it clear to him that it was a gamble and he should expect some hassle if there are issues. We lucked out. This is not always the case.
Refurbished monitors might have dead pixels, backlight bleeding, ghosting etc which are legitimate issues but as the monitor is still "working", you may not be able to claim seller warranty successfully. Since manufacturer warranty is not guaranteed for these, you might have to swallow the loss and live with it.