Entering Moonboard / how to pinch

Dear fellow climbers,
I'm bouldering for quite a while now and I wouldn't consider myself a bad climber (neither a pro, though), I guess I would position myself in the range of 6b/6b+ which would be around V4 or lower V5. But when it comes to the Moonboard, it still seems absolutely impossible to me, even though there are problems at my grade, supposedly. To me, all those holds seem very pinchy, that's why I assume my weakness is my pinching strength. Since I consider my fingers relatively strong (I train on the Beastmaker at home), I guess my thumb is too weak because there is no way to train the thumb on the Beastmaker. https://trackeasy.fun/usps/ https://showbox.tools/ 
Do you guys agree with my assumption, that by improving my pinching strength I would be able to solve problems on the Moonboard? And if so, what is an effective way to work on my pinching strength? Or am I mistaken and the key to the Moonboard is something else?
Thanks for your input!

As a general statement, the thumb is a very under utilized digit in climbing. Ever pay attention to Tommy Caldwell when he floats? He uses his thumbs in crazy ways e.g. the thumbder cling, thumb gastons.

As for the moonboard, the grading system will feel off. Yes, pinching every hold possible or using your thumb in other ways makes a difference (sometimes pinching at the bolt hole). An economical way to train pinch strength is with a 4x4 block with an eyelit that you can attach weights to.  Tension board’s “the block” is a great tool.  Do 4 reps of repeaters: 10 seconds on, 30 off for 4 sets. Or max out for 10 seconds.

Overall, the key to moonboarding is to swallow your ego and keep at it. Eventually your body makes the necessary adaptations.

Good luck and don’t get injured!

Reed

I second Reed's recommendation for the Tension Block, or you can even make your own by bolting or gluing a couple 2x4 blocks together. Also, if you're new to the Moonboard and bouldering regular gym v4-5 (not v5's on Moonboards), just start doing some static hangs off the holds that are giving you trouble. You really can't ever go wrong training pinches.

Many problems on the moonboard are notoriously sandbagged. Start with the easiest problems, which will be around 6A (about V3), and work your way through the grades.
Also keep an eye out for problems which are repeated and commented on. Problems in the app are uploaded and graded by the 'community' which means some 6A problems will actually be closer to 7A.

Kimon Ache wrote:And if so, what is an effective way to work on my pinching strength? 

Get work as a mason. Or a hoddie.

Halbert wrote: Many problems on the moonboard are notoriously sandbagged. Start with the easiest problems, which will be around 6A (about V3), and work your way through the grades.
Also keep an eye out for problems which are repeated and commented on. Problems in the app are uploaded and graded by the 'community' which means some 6A problems will actually be closer to 7A.

I'd say that moonboard grades are about right but that most US climbing gyms have grossly inflated grades, especially at V0-V5. Climbing gyms are profit driven and want everyone to send V0-1 on day one and feel progression right away if they keep at it. Stroked egos = better business.