Healthcare float tank, this model here: https://oasisrelaxation.com/
Basically new, barely ever used.
Comes with everything required to operate except the consumables (salt and water). Pics show the tank itself, and there's a small 3x3 pallet with the supporting equipment. The person who makes this tank is very eager to help people get set up, including with supplies and instructions and everything you could imagine needing for operation.
The top and bottom of the tank separate, and each part weighs 200+ lbs and is awkwardly balanced, so 2-3 people are recommended to move it. I also suggest using a trailer or box truck (small uhaul one for example) to move it - I think it could be loaded on its side in a pickup, but I think the risk of cracking the fiberglass or causing damage due to its awkward weight distribution makes that a bad idea.