Please consider moving this question as-is (no need to recreate) to the proper forum for maximum visibility. Questions written to the users' own "Discussions" space don't get the same amount of attention and questions can go unanswered for a long time.
You can do so by selecting "Move" under ACTIONS along the upper-right. Then search for and select: "Symmetrix Support Forum" which would be the most relevant for this question.
Not tried it but essentially the VMAX would appear as host to the Pure, so providing you can present it with a LUN of the same size or bigger as the source device then you can initiate a session. the support matrix would be a good place to start for the official position.
Some things to think about :-
You need to make sure you're VMAX is licensed for push.
Are you planning to do this hot or cold? (host online to the source or host offline)
I'm not sure that you can use front end zero detection when doing a push, will need to check but it could mean you copy lots of free space to the pure and you'll need to sort that out post migration.
maybe you should ask Pure for assistance with migrating to their array ? I know everyone at DellEMC is champing at the bits to help with this migration
Guys , can you share your lessons learned? I need to do the same : migrate off VMAX to pure m70. Were you able to do this?
Does Open replicator work?
I zoned the max to the pure, and created a host on the pure but the vamp's wwn didn't auto discover and the pure's connection map doesnt show the two connected. Any assistance here?