Elect by the people at large? People who voted for Trump and such? What's the point in an elected institution separated from the government - the government is already elected, and people will mostly vote for candidates from the same parties in all elections.

Besides, "elect a comission of experts" is a contradiction. Experts are not elected. Expertise is not determined by voting. You want to appoint or select a comission of experts, or elect a comission of politicians. These are the choices. Appointment or selection will be done by someone else, likely politicians too.

You just hope some incorruptible competent people will get there by magic. They will not.

If you could do this, just elect a comission of experts to run the country, instead of this "truth comission" that makes sure people are well informed to vote correctly in elections for the real government, which will in turn run the country. Why do the indirection? There is no reason, if you could "elect" good people, but you can't.