Selfhosted or not, you can also make keepassxc portable with a usb drive.
Here is a old thread from redit explaining how to do it:
Dude… KeepassXC has portables for linux, there is no need to mess with wine or mono. As long as you have both portable versions of KeepassXC, you will not have a problem. You can totally have your database sync between OSs.
For Linux, just get the AppImage for the portable.
For Windows, get the Portable ZIP archive.
Shove them both into a USB, you have KeepassXC portable for both OSs on a stick.