Ugh...

It's too late now but you should have definitely pre-finished this before assembly. For spots like the inside of the cabinets/shelving it makes it super hard to get in and do a decent job of it. Sanding, if that's not done yet will be a nightmare, scraping/smoothing impossible. Sanding between finish coats of finish is a less pain but still a pain here too. The door panels will expand/contract, potentially exposing areas you didn't get finish on. Thankfully it's still early spring and the humidity is still low, and those are walnut which won't move as much as some other woods, so that probably won't be an issue.

It's much faster/easier if you pre-finish and you get a lot better results. You have a nice flat surface you can see well and have good access too, you don't have to deal with inside corners so much, it makes glue squeeze out a lot easier to clean up.

My choice for a finish on this would probably be clear like others have said. Because it is a console table and will take some abuse (pulling equipment in/out mostly) I'd suggest a film finish. Normally I'd say lacquer because it's easy/fast, but you won't be get in with a gun/spray can to do that at this point, so it will have to be a wipe on which you can't really do with lacquer. Shellac isn't durable enough and somebody is going to end up putting a drink down on it eventually. That leaves a poly based product. My choice for that would be General Finishes Arm-R-Seal, 3 coats of gloss followed by 2 satin, light 320 sanding between coats to take any dust nubs out. It is oil based which give the wood that nice amber glow you want and is really easy to work with. The only issue with it is that being oil based so it takes forever to dry and stinks the place up. It will be a lot of work to finish this, weeks over a month depending on climate/how fast you work, but if you are careful about it you still should be able to get a decent looking finish on there.

Really nice looking piece.