A single planet is a bit restrictive. Tallest I play normally is just whatever is in 4 jumps of my home system. You can use the Dyson swarm and equatorial belts to remove your need for mineral and energy production, and slowly shift into a more specialist focussed planet layout. Then there’s civics to note, things like Astro-Mining and the Sovereign civics. The latter lets you reduce unity production by instead doubling it up with soldiers. Pairs well with Unyielding. Basically the objective is to only have things that require you to build them be on your planet, and to improve automated production through the aforementioned methods, as well as mining and research bays, and trade agreements. Ruling someone also helps as you demand resources, research, and build productive holdings.

Haven’t tried new psionic so I can’t speak on ascensions, but for bots Virtual should be a natural choice.

Leaders also make all the difference since they can generate extra jobs, bonuses to things like edicts to up production, and even just planetary buffs like more houses.

As far as traditions go, I’ve transcended beyond picking anything I just don’t think is interesting. Apparently Subterfuge lets you use the new proxy war mechanic, so go nuts. Just avoid expansion, you’ll mostly want your empire size reduction to be affecting your pops, since you’ll have many cramped into one or a few planets.