Yes there are tours to mainland Yemen. To be exact Southern Yemen. Even though everybody might discourage you, because there is war over there (in the North), there was no reason to be afraid. What we joined was an absolutely safe tour - at least we perceived so.
At the moment of writing (Jan 2022) you can enter Yemen only by air, flying in from Cairo to Seiyun, a major town in Hadramaut which is under control of the government militias. Already reaching Seiyun is half an adventure, thinking of the check-in process at Cairo's Terminal 1. Because our original permit was (for whatever reason) cancelled by the Yemenis, we lost one day in Cairo (and we won a visit to the pyramids instead), but on the second day we were waved through the total check-in process, and even upon arrival in Seiyun we 7 tourists were treated very politely and got a special immigration treatment (which anyway took a felt eternity).
Yemen is like a visit to the past (to be honest, only if you just ignore the heaps of garbage, in particular plastic bags, which are lying around practically everywhere). Beautiful architecture of the mud houses, which however need a lot of maintenance.
The doors of these houses are a piece of art. But as this art is costly, often we saw those doors in decrepit state.
Contacting the locals was not so easy, in particular we were advised to stay away from women. Which we men did, but our 3 ladies were contacted by local women, and they were quite curious, as we were told.
Countryside is beautiful, villages are beautiful, a fairy tale environment (if you subtract the garbage)
Highlight of our journey was Shibam, the Manhattan of Arabia. Incredible feeling.
And, to repeat, we did not feel insecure any single moment. Hotels are acceptable, food and beverage is quite ok (yes, but no alcohol). The "price" that the ordinary tourist has to pay is more or less to dress locally, such not be be distinguished from locals, at least from afar. As a man, having to wear this caftan (as you see me at the top foto), the only problem is that you cannot make big steps, as the width of that caftan limits the width your steps. But underneath you are practically free to wear what you want (as a German, I learnt the English expression to wear just nothing underneath, which is "going commando". Which some Scots are said to go ). Yes, we had lots of fun together, and I believe whoever joins such a tour at these times, must display a certain disregard for the "more serious" matters in life. Finally, after all of us passed the mandatory PCR test successfully, we were allowed to leave Yemen, flying back to Cairo. By the way, the service of Yemeni Airways is better than expected. And to my surprise, the heaps of luggage that every Yemeni checked in and also took along as hand luggage, could be stored.