I recently got a FOSCAM 3k wifi camera. It supports the RTSP stream standard and CGIProxy commands over http. After the initial setup (mostly just providing it with your network details), you never need to use the official app or cloud anything and it can be restricted to only your LAN with router firewall rules. This is, at least for me, a "good enough" solution that is not dependent on any cloud infrastructure and can be integrated, completely locally, with whatever services you want.