The point of Jool and similar tools (there is also one called Tayga that runs in userspace, if you want) is to translate network traffic between multiple hosts, where some only have IPv6 and others only IPv4 addresses.

If your machine has both IPv6 and IPv4 addresses you don't need to any translation.

Sure, but if your goal is

> I got some services with only ipv6 addresses and want clients with only ipv4 (sadly still exists) to at least be able to reach them.

then that seems like overkill. Although it depends on your network, of course.