This may be of help— though not specifically what you asked for—issue 41 of GPG has an option for the warlock that grants a fighting style i believe there is also 1 fighter archetype and one ranger archetype that grant a fighting style.
There’s a new invocation which is coincidently 9th level called Dire form. It Increases health, damage, ac and size. Should satisfy your need for a battle familiar somewhat.
I can appreciate that, you’re definitely correct.
For our group you can roll Dexterity or wisdom as a default (no narrator intervention required) as long as the narrator hasn’t called for another stat. Probably not much of a house rule in any case