I admire your dedication. You've been doing a lot.

For the router table top, you could maybe go a couple of routes. There are some waxes that give a slippery finish. That would have the advantage that you could redo it as it gets scuffed and scratched, but it's not very hard and it would be a pain to remove if you want to tray something else.

Polyurethane is another obvious choice. It can be tough and has some give to it, but I've also seen poly not adhere well to oak floor (probably due to inadequate preparation and/or poor application technique) - it scraped off very easily. Water-based poly can dry almost too quickly and be tough to get a good finish without brushmarks. I haven't tried solvent-based poly (dunno if it's even available any more).

An alternative might be to simply finish the top as you like then get a sheet of plexiglass or tempered glass and cut holes in the center for the router bit/collet and mounting holes, etc. If it got scratched up it would be easy to replace without needing to work the wood more. It would be smoother than you could easily get with wood. Glass would be more resistant to gouging and scratching, but harder to cut the holes and likely more expensive.

Putting a paper measurement tape or scribing a ruler into the wood might make sense before you apply the finish.

What to choose? Dunno. There are tradeoffs all around.

HTH a little.

Cheers,
Scott.