I have a Sonoff humidity/temp sensor as well as a Zooz sensor. Both show up in the Homekit Bridge app as available devices, but they don't show up on the HomeKit app on my phone. Searching here, the last I see mentioned about this was Nov '22, asking if that was on the horizon. Has that been added?
Where are you looking on the Home app in your phone? Sensors will not be displayed as devices within a room like Switches/Dimmers/Fans.
For example, I have a room called ecobee with one thermostat and four temperature sensors. Here’s what the room looks like on the main page in Apple Home:
When I enter that room, I get a display with a range of temperature:
When I click on that range, I get the reading from each sensor:
They possibly aren’t showing in the room or home view but if you touch the ‘climate’ pill at the top of the page it’ll display them all. That’s just how HomeKit works for sensors; it’s the same with contacts not displaying a tile - you need to click the ‘security’ pill in order to display them.