Idk who needs to hear this but pirate system farming is my favorite way to get 10’s of thousands of nanites pretty quickly. It’s not hard to net 50+k in an hour. You do need a Units bankroll but salvaging a couple Interceptors is more than enough to get started.
Any time I’m exploring the galaxy or searching for the coolest Interceptor in the universe I’ll stop at a pirate system every 3-5 warps to buy out the Suspicious Packet stock (tech and weaponry) and check out the local solar ships.
If I need a pile of nanites quickly to upgrade a ship or something I’ll hit up pirate systems back to back. I go to the station vendor and buy all the tech and weapon packets, and then go to one trade depot and buy them out too. Then warp to the next system and do it again. Once I have a stack or two of each packet I open them all up and sell them to an upgrade vendor.
One stack of 50 nets around 16-17k nanites. You can get a stack of each, tech and weaponry, in about 5-6 warps. It’s FREE REAL ESTATE!