Try https://channelstream.org/ - you can talk via rest calls to it - it scales up to thousands of connections on a single small machine. You have tiny JS WS/long pool clients available with reconnection logic or you can roll your own if you like.
I have Kobo H2O and it works great till this day. I charge it very rarly - maybe every 2-3 months. It reads everything I like. And it was one of the first with IP68 certification.
I think stencil or Lit are more interesting. I'm not sure I'm the fan of small libs like Lit or preact - I think for scenarios where you have more than 2-3 elements you will have less bytes over the wire very quickly.
My dell e5470 will bluescreen 80% of time when connecting a screen via HDMI on windows 10. Nothing like that happens under linux. The "it just works on other platform" is a myth - they all suck in different ways.
Then maybe look at https://lit.dev/ it might be perfect solution for you, stencil i've heard is also nice. Since its custom-elements you just add custom tags and they will self upgrade.
Here you can find multiple projects for free approved and shared by gov agency.