There are very few motherboards, and certainly no ATX boards available through general retailers with PCIe 4 support. And where previous generation have been upgraded, availability is still poor. Not great that you can have a 7002 in your hand but be unable to use it.
supermicro.com - select generation H12
H12DST-B - proprietary
H12SSW-NT - proprietary
H12SSW-iN -proprietary
H12SST-PS - proprietary
H11SSL - rev 2 - ATX (limited availability in compatible revision 2.x)
gigabyte.com Under both 7001 & 7002 sections
MZ01-CE0 - rev 2 - ATX (horizontal power)
MZ01-CE1 - rev 2 - ATX (horizontal power)
MZ31-AR0 - rev 2 - ATX (horizontal power)
MZ32-AR0 - proprietary
tyan.com
only previous generation - Tomcat SX S8026 - proprietary
asrockrack.com or /minisite/EPYC/
ROMED8QM-2T - ATX
EPYCD8-2T/R32 - ATX
EPYCD8 - ATX (claims to be 7002 compatible on main site, but not included in the minisite)
ROMED8HM3 - proprietary