I highly doubt ETFs exists or can be made that give exposure to your privately owned "mom & pop" shops, or even larger privately owned companies.

Make it 10 to 20 blind funds, each with one very broad theoretical goal: “if the country does well, the fund does well” and with different managers, management styles, investment strategies. The funds do not disclose their specific holdings publicly, but do report them to regulators.

Elected officials transfer all their equity assets into one or more funds before taking office and get shares in the fund.

When they leave office, they can receive the current cash value of their shares, without any capital gains tax, or can get their original contributions back, if the fund still holds them.

If the country did well, the fund did well, and so do those who were elected. Optionally, make this available to all government employees at the federal, state, and local levels, and generally to individual investors.

The family owned restaurant down the block is definitely listed on the stock exchange.