How to make any NPC faction Ideology fluid

Many people sleep on Ideology DLC, but that is because they do not realize it's full potential. On game setup you can change Ideology not only for your own faction, but also edit any Ideology from the listed factions.

Each faction has requirements for memes and other things, and you can't give them Ideology without meeting those. Easiest factions to make fluid Ideologies for are those that require only one meme. Those are all tribals (no meme requirements at all), outlanders and rough outlanders, and 2 factions from Odyssey (traders and salvagers). I'll show how to change rough outlander faction Ideology to fluid, but you can apply this guide to any other faction, some factions require two memes so how to do fluid for them I'll explain also.

On Ideology setup screen choose "Create custom (fluid)"
Choose structure and starting meme inline with requirements for intended faction. For rough outlanders it's Ideological structure and Supremacist meme
Now press save button to save your Ideology for later use.

Select Rough Outlanders faction from list on the left, press "load" and select your fluid Ideology that you just saved. And voila, you have Rough Outlanders with fluid Ideology. Don't forget to change your own faction's Ideology so it will be different from saved one.

You can also make their Ideology fluid! What you need is a saved fluid Ideology that meets their requirements. You can make that by 2 ways: reforming your Ideology during game by adding memes that intended faction requires (only for use in the next run). Or you just start a test game, enable dev mode and give yourself reform points to reform Ideology enough times to meet requirements of intended faction and save it for later.
For example you can't load fluid Ideology with one meme for Empire faction because it requires 2 memes (collectivist and loyalist).

As you see here I started a test run with fluid Ideology that has Archist structure and collectivist meme, then reformed it once to add Loyalist meme. I used dev mode to reform instantly, but it can be done without dev mode, just play for a bit and do rituals to acquire reform points. Now I will save it and exit to main menu.

As you can see I loaded fluid Ideology that I just saved for Empire faction with no problems. This all seems like a lot of setup and work, but you only have to do it once, you'll have saved Ideologies for all your next runs ready, you just need to load them for each faction.

You can have full freedom to shape your Ideology experience in the same run, having multiple Ideologies in your colony allows for endless rituals and allows to have more than two types of specialists, you can have them all in one colony. To make Ideologies "compatible" I recommend to set "Diversity of thought" precept to neutral or to appreciated. Everything else don't matter. Enjoy!