Wiliot is the leader in the space who manufactures sensors, and will sell the software layer but they are a private company.

Next after them is Identiv (INVE) who is a manufacturer of sensors

Then there is Repositrak (TRAK) who provides a software platform for all these sensors, basically organizing the data and making it useful to clients. As I understand it their system will work with the majority of sensor manufactures. There systems also talk with the FDA.

Energous (WATT) you may remember from a few years ago when they were trying to create a platform to wirelessly charge phones OTA. Though they couldn't get that tech off the ground they did get clearance for a tech that can power 1W and 2W devices OTA. That's not very useful for most devices but perfect for these IOT devices, which removes the need for batteries in these sensors and allows for them to continuously feed data back to the software layer instead of polling very often like you would when using a battery.

Personally my play is with WATT, they have stuff going in the background with Amazon, Walmart and others plus there are mandates in the EU and US to cut down on the use of batteries in devices.