I got a Fido Float life vest for Polo from someone on YT. It works really well
Polo already tried it out in the bathtub and it keep him afloat. They do run small though Polo measured a tiny size but it was too small. but I got him an xs and it fit him perfectly so you might have to go up one size. Polo likes water he is the only dog in the small dog park to swim in the baby pool
he also has a baby pool in the back yard that he loves to swim in and play with his floatable toys.