Is it possible to get all the colony enhancements in one run? (Soil Nanites, cryoengine, biofactory embro etc)
Yes.
Frequently multiples as well if you explore enough.
All planetary ruins can give these - the larger the greater chance.
Abandoned Mining stations frequently give them, Research stations sometimes, and Habitats never.
Derelict motherships will often give items, and survey ships can sometimes also drop them.
It is also possible (although v. uncommon) to find items within abandoned ships - although these must be the ships that are 'generated' by the procgen,
not the drifting ships that get left behind by battles.
You can also sometimes recover items from Remnant Nexus stations.
All of this randomly generated at the start of the game, and will be fixed for that entire game.
Is it possible to NOT get all the enhancements in one run?
Also yes.
Very likely confirmation bias on my part, but it sometimes feels like the game 'favours' one particular item to shower you with, while others remain elusive.
Can you get some of the enhancements from quests, bar missions etc?
Yes.
There will be a character "with a paper book" lurking in a bar eventually, and they can offer such things for a price.
4 story points for the first one, 8 for the second, etc.