Links to Recommendations, Useful Tips and Practical Information:
Oman:
(November 2019) Previously, visitors could fill in the visa form at the immigration counters at the border and obtain visas on arrival. Now applicants must apply for a tourist visa via the visa website https://evisa.rop.gov.om/ then enter Oman by any legal borders, according to the frequently asked questions section on the Oman Police’s website.
https://www.pwc.com/m1/en/services/tax/me-tax-legal-news/2019/ksa-saudi-arabia-tourist-visas.html
Iran: