This is quite a loaded question. You need some sort of IPv4 to access the IPv4 Internet. You need some sort of IPv4 if you have devices that don't support IPv6.

What you need in each case depends. If it's just to access the IPv4 Internet, you might get away with NAT64 and a single public IPv4 on the WAN interface.

> my static ip addresses are ipv4.

Ok? You can have static IPv6 addresses if you want.