This isn't a "lemon" by any means of the imagination. It's a used, 14 year old vehicle. It does sound like buyers remorse, and I really feel for you on that.
That said, you now find yourself at a crossroads. Your Tacoma with 138k, Has a new axle, and needs a transmission, has a power steering leak, and a noisy bearing. The bearing and power steering rack isn't too terribly expensive, nor difficult to do. Realistically you could DIY a lot of work, and have a professional do the difficult final bits (Press the bearing in and out of the spindle, and do the alignment after the rack is replaced - if it needs to be).
You can either sell it and take the loss. Or put in a new transmission (and upgrade to an external transmission cooler if it doesn't have one), finish the other bits and keep on building.
I don't want to be rude. I will be blunt. If you think Overlanding or Offroading "carefully" means never having a breakdown or cost expenditure on a vehicle. You are clearly mistaken.
I wish you the best of luck in your choice.
FWIW: I bought my 2001 4Runner for $5k. With all the upgrades and $hit I have broken Overlanding and Offroading. I'm $18k into it total. Wouldn't change anything I've done, if I could back and do it all over again.