Should I move to Portugal before or after selling my company?

It is usually the single most valuable sequencing question you will ever answer. Sell while Norwegian-resident and the gain is taxed in Norway at known rates; move first and the exit tax is measured at departure anyway — on the unsold value. Sometimes a pre-departure sale wins, sometimes the 12-year election wins; the difference is routinely seven figures in NOK. Model both orders before signing anything, with real numbers.