I've been in contact with immigration in Suratthani and got some answers, mainly for people with non-b and WPs.
The 7 day extension can be done only once. After that you will have to leave the country for a 90 day stamp on a multiple entry non-b visa.
If you get the letter from your embassy you will get a 30 day stamp, this has no limit on how many times you can do it. And it won't void your non-b and you can do a border bounce once they are open again.
Did not get any clear answer what can be done if your non-b is up for renewal other than the embassy letter will allow you to get 30 day stamps until borders open again.
I've asked my lawyer to contact them on Monday to see if we can get this in writing.
TLDR : Answer Summary
The post discusses options for extending the stay of individuals with a Non-B visa in Thailand, particularly during the COVID-19 pandemic. It details the process of gaining a 7-day extension, the alternative of obtaining a letter from the embassy for a 30-day stamp, and the challenges related to renewing a Non-B visa. The responses highlight the necessity of verifying information and seeking formal confirmation regarding visa extensions.