You can create up to 8 different simultaneous drum pieces per FM-X Part and modulate parameters on different beats to create more than 8 (only 8 active at one time).  Less if you use algorithms with modulators.

FM-Xperience by Easy Sounds has FM-X kits (at a cost).  I think there was a promo library from them with FM-X drums that can be downloaded at no cost.   Maybe they're in Montage Expanded.

Welcome to the forum! Possible? Yes. Easy to do? No. Are there other considerations? Yes.

I have seen that some drum sets are flagged as AWM and FM-X.

Are you seeing that in Category Search on the instrument?

One observation is that the AWM2 part of a combo awm2/fm-x drum kit is usually, but not always, a DRUM part and the FM-X parts in the 'kit' may, or may not, be doing any 'drum' work at all.

My question is: Is it possible to create drum sets where each sound is actually a FM-X element so that each drum sound's parameter are tweakable?

Yes - but there are some limitations as well as some other things to consider depending on your actual needs.

Phil 'Bad Mister' Clendeninn explains that in detail here:

https://yamahasynth.com/community/modx-series-synthesizers/bright-drum-kit/#post-119617

An actual drum part has different routing options than an AWM2 or FM-X part and useful 'Rcv Note Off' and 'Group' parms that the other engines don't have. If you need either of those parms you need a drum part.

A drum part has 73 'keys' labeled C0 to C6 but an AWM2 or FM-X part only has 8 elements or operators. If you need more than 8 drum sounds you need more than one part for those engines. And even if you use all 8 keyboard controlled parts you still only have 64 elements/operators.

And because you've used all 8 parts there aren't any parts left for other sounds.

There is a fairly steep learning curve for programming FM-X sounds. How steep depends on your current level of FM programming. As the other responder mentioned there are 3rd party offerings for FM-X based drum sounds and sets.

We have two suggestions for you:

1. The Modx has several dozen preset drum kits. You can create your own customized kit by starting with an 'Init Drum' and then copying individual keys from those other drum kits to your own kit.

2. If you have a specific, actual need, create a new thread and post ALL of the details of what you need help with.