Perhaps I'm missing something but I don't think you need your second stats.
At any rate what you are looking for is to put | eventstats at the end of your search like
source="mysource" ImmediateAction=Block | geoip SourceIP | stats count by SourceIP_city, SourceIP_country_name | eventstats sum(count) by SourceIP_country_name
If you wanted to get crazy I always like doing something like this
source="mysource" ImmediateAction=Block | geoip SourceIP | stats count by SourceIP_city, SourceIP_country_name | sort -count | stats sum(count) as Total_Events list(SourceIP_city) as City list(count) as Count by SourceIP_country_name | sort -Total_Events
The problem is if you export this to a scheduled PDF the columns for the second stats split-by are put at the bottom. If you export it to csv the mv list fields are space delimited. Looks nice in Splunk though 😃
Depending on what you are looking for you could chain a couple stats commands to act like a mini drill down. Something like
source="mysource" ImmediateAction=Block | geoip SourceIP | stats count by SourceIP_country_name SourceIP_city | stats sum(count) as count by SourceIP_country_name
That will give you JUST the data by country but if you click the country it will go a step down and show you the individual line items for "City" within that country without taking you directly to the raw data (third click will).