You are in for some pretty serious work.
You’re right that water pipes are easy to relocate. Drains are a *lot *harder. If you’re lucky, once you pull up the floor, you’ll be able to “simply” shorten the toilet’s drain and move the floor flange straight along the existing line. If you need to extend the line or turn a corner, well, the job just got harder. What makes it hard is that toilet drains are usually cast iron - cutting and joining the stuff is in the realm of “very advanced do-it-yourself” or “call a professional” to do. Newer homes may use PVC, which is more DIY-friendly, but it’s not been commonly used except for the past few years, and even then, it depends on your particular state or county’s building and plumbing codes.
There may be structural concerns as well - those big cast iron pipes can’t just be passed through a hole drilled in a floor joist - if you need to cut joists, you may want to consult with an architecht before you cut too far and the floor suddenly grows in size as the walls move apart.