You have two servers as you mentioned with 32 cores each, windows server 2025 requires 16 cores per packs on standard bases.
Physical Cores: 2 Servers × 64 cores = 128 cores to be licensed.
Standard Stacking: Since you have 9 VMs, you must license the physical cores 5 times per host (which gives you rights for up to 10 VMs).
128 cores × 5 = 640 core licenses.
640 ÷ 16 = 40 Packs of Standard.
Datacenter: You only license the physical cores once.
128 cores ÷ 16 = 8 Packs of Datacenter.
To verify if the packs cover the 9 VMs you have there according to Microsoft's licensing rules and link here Windows server OS standard 2025 40 packs total should be right.
Buying 8 Packs of Datacenter is the cheapest way to do this. Buying 40 Packs of Standard is a waste of money