Are there any standards for 'Smart' road signs?

Something that occurred to me - there’s a lot of effort being put in to recognize road signs; but for bespoke signs its going to be a lot harder to know what they mean.

At this point, it becomes a lot easier for a road sign to feature a QR code and a JSON payload - ie: max load limit on a bridge is X units.

I’m wondering if any countries had trialled this.

All I could find was thinks like:

It seems like a really good first step would be to take something like the current openstreetmap schema and really flesh it out into a full blown standard; then make a bunch of one click “print this as a QR code you can stick on a sign” tools for a JSON/recognisable version of it.

I’m not sure if sticking stickers on official road signs is legal, it could be seen as vandalism.