KeepassXC (https://keepassxc.org) combined with:
* It's browser plugin (https://addons.mozilla.org/firefox/addon/keepassxc-browser/)
* Syncthing (https://syncthing.net/) to synchronize across devices and mobile
* Keepass2Android Offline for Mobile access (https://play.google.com/store/apps/details?id=keepass2androi...)
Then the experience is close to Lastpass but only using opensource components.