So basically I need another SSD that's empty. Then I need to put OS on it somehow. Maybe hook up the optical drive it it still works I guess.
Then with W10.. will I be able to go into each of my previous drives and recover the data?
No you could you use a bootable USB OS - as mentioned above.
All you need is 8Gb USB pen drive and make a bootable Ubuntu USB stick (Ubuntu Live) - it will load the OS (Ubuntu - Linux based OS) via the USB as it boots and will be able to access all drives attached once loaded.
So, once created, boot from the USB stick (first bootable device in BIOS) - have all your drives attached when you boot it up - and you will be able to identify each drive and copy files over for saving using the Ubuntu interface (OS).
That said - you may find it confusing; the making of the OS and then the use of Ubuntu itself, as you're unfamiliar with the processes involved. It would be a lot to talk you through via a forum - so you will need to do research on your part.
Suggest you look at this -
Clicky - walks you through the process of creating Ubuntu Live using Rufus, a tool for creating a bootable USB devices.
Then watch beginner tutorials on YouTube to get an idea of how to access drives and transfer files.
Also. What about getting like 128gig of M2 drive and putting os on that? That sounds cool
No, waste of money - and no real life gains for your usage. You would be better off getting a larger SSD for the money.