This is for a closed system that unfortunately sometimes is supposed to be available outside[1] - a touch screen panel UI for (big[2]) embedded system.
It's hard to impossible to properly guide OS outside the browser regarding what keyboard we want at different points in time unless we end up also implementing custom keyboard plus some way to talk with it from JS. Previously we used a Chromium extension that could bypass some of the issues because it had privileged access and thus could send "secure" events.
EDIT: For some extra context - for reasons of ease of use, we want the keyboard of appropriate type (numeric, qwerty, other specialized layouts) to show in position related to actual input field, not take entire lower part of the screen like typical on-screen keyboards. For dealing with possible edge cases or otherwise making it more accessible, we also provide for the keyboard to be draggable by user.
[1] Sometimes it's accessed externally instead of in-person, for various reasons this means we have both the ability to open the web interface and use VNC.
[2] By big I mean we have a complete PC running Linux there, with intel CPU/GPU and an SSD
