However, even ECMWF admits there're issues with 10m ground levels (see the article). Especially we will experience high inaccuracy for higher altitudes, stronger winds or complex orographies.

For mountainous areas, it is important to use a high resolution model if available where you are living.
A 9km resolution model like ECMWF model cannot perform in mountain. And worse, the orography model which gives to the weather model the terrain details is very coarse.

In the Meteogram, try Meteoblue which provides good forecast in mountain. It is available only at point forecast, but it includes a good correction of inaccuracies due to the altitude.

would it make sense to extend meteogram and show wind at altitude?

This is available with Airgram, useful for flying.

thanks for explanation, now I understand the issue with wind at ground level at 10m height. Truly you're right, most models do use the some extrapolation,
ECMWF for reference https://confluence.ecmwf.int/display/FUG/9.3+Surface+Wind

However, even ECMWF admits there're issues with 10m ground levels (see the article). Especially we will experience high inaccuracy for higher altitudes, stronger winds or complex orographies.

As base meteogram is a tool of daily use (as a pilot I check before I go hills to fly, for tourism in mountains the same, before I go ridge hike I check wind), would it make sense to extend meteogram and show wind at altitude?

People can really misjudge situation based only on 10m extrapolated ground wind.

Thanks for answer!