You could use it for that…
Personally, I prefer circumaural headphones for most times except for working out. The gym is one of the most brutal environments to use headphones. These Sennheiser closed back ANC headphones would not be worse than other fullsized closed headphones, but there are still things to consider.
Pros:
Lightweight
Wireless
Active Noise Cancelling (ANC; for focus)
Airplane mode for meditation (no Bluetooth or music, just ANC)
Adjustable transparency mode (opposite of ANC, allow conversations and gym noise in, and you can adjust the transparency volume)
Works as a remote control
Can answer (or decline) calls
Comfortable clamp pressure
The solid-wrapped pads would be easy to wipe off sweat.
ear pads are replaceable
nice sound quality, probably much nicer than the loose, boomy gym speakers in a loud echoing room.
Earcups twist flat case to use when taking a class with a fitness instructor (Zumba, Aerobics, Yoga, etc)
Cons
Closed back holds heat
Pads get warm/sweaty
Dry cloth for cleaning recommended; sanitizer gel or spray will shorten the life of the pads (make them dry out and eventually crack)
Comfortable clamp = light grip, headphones may slip around with movement or leaning
We tend to bump and bang into things at the gym: you might accumulate scratches and scuffs on your high-end headphones.
Momentum 4 twists flat, not folds into the smaller ball of previous generations (duffel bags are big, this is a mild concern, but it could be awkward sitting on top of textbooks in a school backpack)
Overall, the Momentum 4 does have a few particular advantages (especially the adjustable transparency mode and airplane mode), but I find the gym a harsh environment, and I personally prefer True Wireless in-ear headphones at the gym because they don’t make my ears hot and silicone eartips are cheaper to replace. Hopefully I provided enough detail for you to choose if it’s right for you.
Sennheiser uses MAP for authorized dealers, so prices should be the same unless there is an exclusive model (like the HD 58X Jubilee). Buy from wherever you wish… many here have Drop store credit from their rewards program.
One of the features on the main product page (https://www.sennheiser-hearing.com/en-US/p/momentum-4-wireless/) is "Crystal-clear Calls". Under the detailed specs, the mic pick-up pattern is listed as "2 mics per side, beamforming for noise reduction". In short, yes.