Welcome to the forum.
Since gold prospecting with a metal detector seems to be a big part of your plan, you might want to check out Detector Prospector.
The most proven, (released 4 years ago) do it all very well, VLF which includes gold prospecting is definitely the Minelab Equinox 800. It can handle the high mineralization in most of the gold fields in the states you mentioned since it can operate in single frequencies high enough for small gold nuggets and in simultaneous multi frequency which also hits hard on small gold nuggets but also ground balances really well when the ground has lot of iron mineralization. The Equinox 800 is also a proven coin, jewelry and relic hunter on dry land, fresh water and saltwater beaches. If you buy one and like it, there are several affordable aftermarket collapsible carbon fiber shaft systems for the Equinox that make it easy to backpack. It also has two great gold prospecting and trashed site coils in the Minelab 6" coil and the Coiltek 10X5" coil.
If you happen to be using it near or in water it is supposed to be waterproof. That has been proven to not be the case. If you buy a new one you are covered for 3 years anyway.
The recently released SMF Nokta Makro Legend is very similar in performance to the Equinox 800 for coin, jewelry, soon to be relic and gold prospecting (when the next software update is released). I wouldn't hesitate to use it in the Western USA goldfields and relic sites after the iron bias settings are updated. Rugged, heavy duty (and a bit heavy) with a 6" round coil and a 10x5 coming soon.
The recently released SMF XP Deus 2 on paper, is capable of being an all around detector that has a gold prospecting mode. I can vouch for its coin, jewelry and relic abilities. They are outstanding. It also is dive rated to 60 feet depth. It's lightweight ergonomics and packability are also unmatched. There have been a couple of reports from guys I know and trust in Utah and Nevada along with a well-known Arizona YouTuber that have been able to find small gold nuggets with Deus 2. However, they all have found (me too) that Deus 2's Goldfield mode needs much more sensitivity to very small gold below .3 grams.
Finding the smaller sized gold near the surface often leads to the bigger stuff so many gold prospecting detectorists use one detector to find the crumbs and another detector for the bigger/deeper nuggets. Most serious gold prospectors using detectors also own a pulse induction detector like the Minelab SDC 2300, GPX 4000 to 6000 series or the GPZ 7000. The numbers in the name of those detectors reflect their MSRP unfortunately.
For the Western USA and its sometimes wildly changing iron and salt mineralization, these newer SMF (simultaneous multi frequency) VLF detectors are a very welcome addition to detector enthusiasts out here.