Peel and stick tile

Only if the grout lines are very small. Otherwise, the peel-and-stick will crack at the grout lines from the weight of people walking on it.

I have never tried peel n stick tiles but have used vinyl rug over shattered ceramic. I purchased vinyl floor filler (similar to spackle) and filled the grout lines and shattered areas until level then laid the vinyl. Good luck!

If as a temporary fix only. Eventually the seams will fail. Always best to have a proper sub floor for the best results and long wear.

https://www.youtube.com/watch?v=U3ofs4L7x3o

I think you will have to replace the peel and stick tiles often.

You would need leveling cement or something first. It would look fine for awhile, otherwise, but it is fairly soft material and would sink into the grout lines.

I wouldn't. You will have a mess later. I have an old house and after living here for 15 years I began to wonder why the kitchen floor was over half an inch higher than the rest of the house. So I started peeling off flooring. 6 layers later (wood tile, underlayment, tile, Masonite, tile, linoleum) I finally found hardwood. I'm still trying to get the glue off of it! Take the time and effort (and maybe money) to remove the tile and be sure there is a good sub floor under whatever you use. You'll be happier with it and any future owner will be happier with you!