I think the more reasonable take on this would be starting in early space age, and starting by developing your system (starbase, stations) and your planet's buildings before inventing FTL travel.
Many of the otherwise starting techs wouldn't be researched. But it would also mean being stuck in your system for a while, and at a huge disadvantage.
And the earlier stage you'd be looking at (stone age?), the more limited your options are, limited to a single planet. Sure, there could be special buildings and maybe districts, like the current primitive buildings, to reflect the civilization stage.
But, it'd end up being a lot of work for what seems to be a purely roleplay feature with little gameplay purpose.
Many of the otherwise starting techs wouldn't be researched. But it would also mean being stuck in your system for a while, and at a huge disadvantage.
And the earlier stage you'd be looking at (stone age?), the more limited your options are, limited to a single planet. Sure, there could be special buildings and maybe districts, like the current primitive buildings, to reflect the civilization stage.
But, it'd end up being a lot of work for what seems to be a purely roleplay feature with little gameplay purpose.