Did the calculation on the population of Core sector based colony sizes. By this metric, the Core sector is between
177 million and 1.7 billion total population.
The whole of the sector could fit on a size 10^8 planet in the lower estimate and a size 10^9 in the upper estimate. For comparison that's the population of Brazil at the lower estimate and the population of the China and the USA combined in the higher estimate.
Made some graphs from the data:
There are 62 populated planets in the system (including decivilized population planets). Three are decivilized by default (not counting generated decivilized). The average planet size is 10^5, and there is only one size 10^8 planet in the whole system (Chicomoztoc, Aztlan Star System capital of the Hegemony).
The distribution of the planets by ownership is pretty even, with independent and pirate colonies making up a large portion.
However, when you organize planets by population size, the only size 10^8 planet makes up over 50% of the sector population (Chico).
Which means that when looking at the sizes of factions by population, the Hegemony pulls far ahead of the rest with it's size 10^8 and other large colonies. Tri-tachyon is tiny by comparison (making them the literal 1%). Sindrian Diktat, while only having 3 planets, has two size 10^7 thus they punch up way above their planet count.
Here's a graph with Chico left out. As can see, the other factions with larger numbers of size 7 planets begin to pull way ahead of the Hegemony.
If you take out the factor of 10, you get a graph that looks fairly balanced with how powerful each faction is framed. Hegemony and Persean are head to head, Tri-Tachyon small but still powerful, and Sindria a minor regional power.
I'd take this all with a grain of salt. Interesting seeing how much the difference of a power of 10 makes. Makes size 10^9 and 10^10 seem impossible for the sector, so glad they got capped.
There are worlds with the decivilized modifier or had population before. Rough estimates of their population:
Maxios (5-6), former capital of Maxios system it is now looted and devolved into chaos. Would have been as large as Novis Maxios at least.
Crom Croch (3-4), a mining colony destroyed after the collapse.
Hannah Pacha (6-7), description says millions dead so at least 10^6.
Opis (7-8), capital of Askonia system, was destroyed by a planet-killer causing the Askonia crisis. Considering the large refugee population on the other planets in the system, very large population.
Killa (3-4), attack on their domes and left decivilized.
Mariaath (6-7), was devastated by the Luddite attack and had a strong enough military to oppose Hegemony expansion was fairly sizeable. at least bigger than it's current state.
Zorrah (3-4), used for resource gathering by the Hegemony so unlikely to have ever had a large presence if any.
Using these very coarse assumptions, 12 million to 1.2 billion lives have been lost.
It would take 177 10^6 (1 million people) colonies for the Player to have as much population as the core sector using the lower estimate. It would take about 17 colonies if the players colonies are counted for 9.99 million while the rest of the sector counted 177 million.
(poorly organized) Data:
https://docs.google.com/spreadsheets/d/1KSDkr3VSk_XvkW8mc6H2diKau_6583W5h7mFDSd6djk/edit?usp=sharing