The HMD Asha 305 in fact runs Android 11. It's called PulseOS due to the fact that it doesn't run Google Mobile Services, and many of it's apps are web apps/lite versions like Facebook Lite and TikTok Lite
The HMD Asha 305 is arguably one of the most unusual smartphones on the market, as HMD Global has incorporated a 5-inch display and a removable battery into a design that is more reminiscent of the early days of smartphones. With an operating system called Pulse, the device is designed to replace Android smartphones.