Configure/Override EU Cookie Compliance I've installed eu_cookie_complience module (eu_cookie_compliance 8.x-1.9). The documentation is nearly non-existent, but as much as this module is used, I'm hoping to find someone that has solved these issues.

The big one: how does one set the eu_only parameter to true? Crazy, but there does not seem to be any option in the Admin panel. I could hack the contrib yaml or worse the module and force things. But that's a bad idea.
How can I hook into or override eu_cookie_compliance and specify my own IP lookup. Though it isn't documented, apparently there are three ways to check to see if the user is EU (the smart_ip module, the geoip module, or geoip_country_code_by_name())  We already use IPSTACK and I want to leverage that.
The settings form is hard-wired to only display the config field on the form if one of the following is installed: the Smart IP module, GeoAPI module, or the PHP geoip extension. Outside that you'll have to bypass the config form; if you're version controlling your config, make the change in the eu_cookie_compliance.settings.yml file; or use drush cset to make the change directly.
The hooks are documented in eu_cookie_compliance.api.php. You're wanting to use hook_eu_cookie_compliance_geoip_match_alter() that lets you alter the results from the eu_cookie_compliance_user_in_eu() function. The parameter $geoip_match is a keyed-array with country &amp; in_eu keys that drive the logic.