8 groups - top 2 qualify - most simple way.
Assuming Russia is back and in a non-hosting year for UEFA, that would mean 7 groups of 6, and 1 group of 7 (10 games for most groups, 12 for the group of 7), and if this world cup's qualifying had used that system, the pots would have been:
Spain, Netherlands, France, Croatia, Denmark, Portugal
Italy, Germany, England, Belgium, Switzerland, Austria
Ukraine, Sweden, Turkey, Wales, Hungary, Serbia
Russia, Poland, Romania, Greece, Slovakia, Czech Republic
Norway, Scotland, Slovenia, Ireland, Albania, North Macedonia
Georgia, Finland, Iceland, Northern Ireland, Montenegro, Bosnia & Herzegovina
Israel, Bulgaria, Luxembourg, Belarus, Kosovo, Armenia
Kazakhstan, Azerbaijan, Estonia, Cyprus, Faroe Islands, Latvia
Lithuania, Moldova, Malta, Andorra, Gibraltar, Liechtenstein, San Marino