The reality is that the odds are very slim that your two cats will find a new home together. There are just very few adopters looking for multiple adult cats compared to the numbers that are available due to owners passing away, families getting evicted, and yes, surrendering them due to allergies. So unless you find a person on your own that is willing to take on your cats, you’ve pretty much sentenced them at best to a very long stay in a shelter as they wait to be adopted, and at worst being put down in a cold clinical room alone and scared. They also might not get adopted together which is also traumatic for them. There are many articles written about how animals in shelters show clear signs of depression if they stay there too long and many more about the realities of older animals getting adopted.

I’m not judging you if you consider all of that and still are left feeling you have no other alternative to solving the situation you find yourself in. But you’ve spent all of these years taking excellent care of your cats, and it’s likely not just a simple matter of them having to adjust to someone new filling up the food bowl. It’s a VERY scary and horrible experience for your cats. All of that is why so many people are on this thread encouraging you to explore every option possible to resolve this without giving your cats up.

BTW, I have been at work 12-14 hours a day most of my career, and my cats are all fine, so not being home as much as before isn’t something you need to be concerned about. That’s a minor adjustment for them.