If it has a decent camera, use it as a dedicated webcam. If the camera is just okay, convert it to a car dash-cam or a home security camera with integrated UPS, storage, and even fallback connectivity via mobile networks. Use it as a dedicated gaming device, or a music player for non-IoT speakers. Convert it to an LTE modem and make it a fallback for your home internet. Run a Monero node on it. Or a Briar mailbox. Host a personal website on it and make it available via DynDNS. Make use of the phone’s sensors, e.g. the light sensor or the microphone for home automation. Connect it to speakers and use it as a Bitcoin price monitor that plays “You Suffer” by Napalm Death every time BTC passes a certain threshold. Or just use it as a digital photo frame on your desk.