The official fiqh in KSA is that of the Hanbali fiqh, one of the 4 recognized madahib in Sunni Islam - only few minor and cosmetic differences between them, which Muhammad ibn Abd al-Wahhab al-Tamimi, surprise, surprise, also followed.
At the same time we have the most diverse local followings in terms of different madahib. In Hejaz and Tihamah the most popular madahab is the Shafi'i one. In the Eastern Province, among the Sunnis, the Maliki Madhab is the most popular. In the North, around the borders with Iraq and Jordan the Hanafi madhab is the most popular one. In Najd the Hanbali madhab. All 4 major madahib in Sunni Islam.
Among Shias we have the Twelver sect in the Eastern Province and the Zaydi Shia's in Najran Province.
Quite diverse I would say, in fact more diverse than anywhere else.
Nobody calls himself a Shafi'i Muslim do they? Maybe I should do that and most Hejazis and Yemenis who happen to be Sunni Muslims of the Shafi'i fiqh.
Muhammad ibn Abd al-Wahhab al-Tamimi did not invent anything new and I challenge anyone who says he did to prove that.
We have had this discussion several times and nobody has been able to prove anything. Ironically it has always been the words of a certain tiny minority (Shia Twelvers) who only account to 8% of all the world's 1.7 billion Muslims while we Sunnis, regardless of madahib, account to 90%.
I wonder who has a different interpretation of Islam and who has not....