You can’t/shouldn’t leave. You can’t get your marriage extension in time. So the advice is to get either a visiting family or Covid extension. Great advice.
But, after this extension, you still have a valid multiple entry, unexpired visa. You have a choice then approaching the end of your family/covid extension. You can extend it. Or, you can leave the country, do a ‘border bounce’ and come back on another 90 stamp on your original Multiple Entry visa up to its expiry date.
Obviously this is only useful if the border restrictions are loosened, or if you don’t have the funds to extend in country.
I did this years ago. Multiple entry visa, got a job, an annual extension. 6 months later I quit my job. Cancelled my extension and then just left and came back in on my original visa. Did 3 more border bounces on my original visa, including one on the very last days before it expired for another 90 days.
If it’s a spousal non-O that has a work restriction, it’s impossible (retirement ones cannot be switched either). It’s because the restriction was in place as a condition of your visa.
Otherwise, as stated above, you should be able to get an extension based on work using your Non-O
You get a 30 day, under consideration stamp. It’s 30 days from the day you applied. Just apply earlier, perhaps a month or so before your visa expires. You don’t have to wait until it’s about to expire.