Martin Kehrwald. There are flights from BKK to Phnom Penn, which is the easiest and cheapest route, but BKK can pose a lot of problems for those with extensive covid extensions. Suggest your friend follow John Stanners advice and do the visa run through Singapore returning to Chiang Mai.
Martin Kehrwald. It means part of a tour group. There has been reports in another group that no tourist visas are available from the Embassy in Laos. At this moment the only way to do a "visa run" is by flying to Phnom Penh, and applying to re-enter Thailand with a Thailand Pass. Be wary however, that some people are being denied re-entry into Thailand on account of having extensive history of "covid extensions".