My biggest concern about a "generic plugin" would be that the strength of Adobe Analytics is in the customization of it, and I don't think any sort of generic plugin would be applicable to most users...
That said, have you considered building a custom data layer into your client's wordrpress themes, or create your own wordpress plugin that would allow you to create a consistent way to collect data for all your clients?
https://developer.wordpress.org/plugins/intro/
If you create your own plugin, you can ensure that all the data you want to collect, in the format you want to collect it would be coded by you and integrated into all your clients' sites. I would still recommend that your own unique plugin would leverage a data layer, and that you would have a Launch property set up to use that data layer efficiently...