For those concerned about the economic implications of collecting/creating your own fuel, let me tell you a story about a game I used to play.
You might have even heard about it.
Elite. Specifically in this case; First Encounters.
Spoiler
It was possible in this game to fit some ships with a dedicated fuel scoop which allowed you to collect fuel from various places, which in turn allowed you go wandering on quite a large scale.
There were however some caveats.
Firstly, the places you could collect fuel were limited to stars, brown dwarves, and gas giants.
All of these places have very strong gravity wells and it is possible to get pulled into an unrecoverable dive, so using the autopilot is not a good idea. Manual flying all the way while scooping.
All of these places have an "atmosphere", so you need atmospheric shielding otherwise you'll burn up.
Stars and dwarves are hot so you need at least 1 shield generator so you can get close enough to any gasses without burning, and even then the heat will bleed through the shields and slowly bake you so you have a limited window to collect before you are forced to back off and cool down.
All of these places are usually "in the sticks" of thier systems, so there is zero police presence and you can more or less count on someone trying to jump you while you're busy trying not to die by stupidity.
Then, you can only collect standard hydrogen fuel. So if you want a military drive you can't scoop as well.
This means using civilian drives which are bulky.
You also need free cargo space, usually lots since civilian drives (especially the larger ones) are not very efficient and gulp fuel.
And on top of all this you MUST have your drive serviced at least once a year otherwise it breaks and leaves you stranded.
So your ship has to have a very specific configuration which is (for smaller ships) not optimal for combat, and you are range-limited by how far you can jump out and back to civilisation in a year.
You can turn your ship into a giant flying tanker and scoop fuel for money, but it's both fairly tedious and not very profitable for the amount of capital you need to set it up.
I would say most of these things could also apply to Starsector in some degree.
Hazardous environments.
Specific equipment/loadout requirements.
Time requirements, leading to;
Potential harassment by hostiles.
The way I see this working in SS is:
Can collect from; gas giants (cool and sensible), nebulae (slow, low efficiency), stars (rich, but do you feel lucky?)
You need; any ship with a fuel scoop and relevant protective hullmods to collect, and at least one tanker class ship to refine
Approach collection site - RNG check for hostile encounter
Check for presence of scooping equipment in fleet - if zero do not continue
Commence scooping
Time skips forward <arbitrary time length> so the player isn't waiting around - if previous hostile RNG was zero check again now
Amount of fuel collected is based on some combination/ratio of the cargo space and speed of the collecting ship(s)
This fuel is raw and unusable, it needs to be refined first - remove <some proportional amount> of supplies to simulate this, bigger tankers are more efficient
Maybe reduce CR for any ship fitted with scoop equipment
Fleet now has more fuel at the cost of time and supplies
You could also have scooping in already devloped/claimed systems be treated like theft in varying degrees.
Potential for sensor/reputation shenannigans etc.
