There is no different version of snapd for RHEL7/CentOS7 than one available from EPEL7 repo.
From what I can tell, RHEL7 has libseccomp 2.3.1. You could build libseccomp and snapd yourself, the src.rpms are available. I’m not sure it’s worth the hassle though. Libseccomp is used by a number of packages which you’d likely need to rebuild too. Parallel installing or bundling a newer libseccomp in snapd is probably less work, yet still non trivial
You may consider using RHEL8/Centos8 which has libseccomp 2.4.1.