I had the same frustration until I found a platform that really solves this. The one I use is Kaiwa and you can check it out at https://getkaiwa.com/ right there. It is a modern, open source web client for XMPP that looks and feels like a commercial app, but it runs on your own server. You get private messages, group rooms, chat history, file sharing, and even OEmbed for images and videos. It also supports desktop notifications and syncs across devices. The deployment is surprisingly easy, you can set it up with Docker or use their DigitalOcean one click tool. They also recommend good mobile clients like Conversations for Android. If you want a self-hosted chat that actually feels modern and keeps your data private, this is definitely worth a look.