I was just lucky last year on the sale of some property and upgraded every thing except my printer. This is rare for me and considering my age, may be my last purchase of better cameras. Let me make some suggestions. I owned the original Nikon Z6 and liked it but never understood why it wasn’t designed for two memory cards. I traded it to B&H for the 7ii. The colors will just blow you away they are so good. It has two slots for memory cards and instead of taking the lesser CF Express A cards that Sony chose, Nikon opted for the Type B memory cards that are faster. Sony makes both. But, I also have the Z9. It is a seriously professional camera that is heavier and obviously not for everyone. However, I do video that I plan on selling and continuing to use for the same in the future. I love this camera. The weight doesn’t bother me and it is just feels far better made than any camera on the market. For what I do it was perfect. If not for the professional video, I would go with the Z7ii in a second. Here’s the kicker. Because I’m such a fanatic about quality, I purchased a Fuji GFX 100s and it blows everything on the market away for still life’s and landscapes. You have to see the difference in resolution between it and a full frame to appreciate the quality of a medium format. This is also a commercial camera and I will not buy the next best thing. My wife loves the Zii and I’m thrilled with the Z9 and GFX for the purpose they were purchased. Considering that you want an upgrade but am not a professional, I would choose the 7ii. You will not be disappointed. It is a beautiful camera that never ceases to amaze me with its quality build and fantastic photos.

I was just lucky last year on the sale of some property and upgraded every thing except my printer. This is rare for me and considering my age, may be my last purchase of better cameras. Let me make some suggestions. I owned the original Nikon Z6 and liked it but never understood why it wasn’t designed for two memory cards. I traded it to B&H for the 7ii. The colors will just blow you away they are so good. It has two slots for memory cards and instead of taking the lesser CF Express A cards that Sony chose, Nikon opted for the Type B memory cards that are faster. Sony makes both. But, I also have the Z9. It is a seriously professional camera that is heavier and obviously not for everyone. However, I do video that I plan on selling and continuing to use for the same in the future. I love this camera. The weight doesn’t bother me and it is just feels far better made than any camera on the market. For what I do it was perfect. If not for the professional video, I would go with the Z7ii in a second. Here’s the kicker. Because I’m such a fanatic about quality, I purchased a Fuji GFX 100s and it blows everything on the market away for still life’s and landscapes. You have to see the difference in resolution between it and a full frame to appreciate the quality of a medium format. This is also a commercial camera and I will not buy the next best thing. My wife loves the Zii and I’m thrilled with the Z9 and GFX for the purpose they were purchased. Considering that you want an upgrade but am not a professional, I would choose the 7ii. You will not be disappointed. It is a beautiful camera that never ceases to amaze me with its quality build and fantastic photos.

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When I went mirrorless, I started with a Z6 and a Z7.
I now own both Z9 and kept a Z6, which I use mostly for astrophotography or low light indoors. I tested the Z6Ii directly against the Z6 and despite other claims here, other than a few clicks faster FPS, could not discern enough difference to upgrade. I’m waiting on the Z6IIi to see if I want to upgrade.

The Z9 took me to places I’ve never been with the ease of shooting action. And it has been fun to learn new techniques and an almost entirely new mindset about autofocus. I shoot mostly sports and BIF. I now use my Z9 for just about everything, including Astro. The only drawback is size and weight. The Z9 is mostly a budget decision.

I see you have a 150-600, so you are obviously shooting some wildlife or action sport. I left a D7200 behind for the D500 as my interest in action grew.
You will be fine with a refurbed Z6 II or Z7II. Both will be a tremendous upgrade. Get a 24-120 f4 lens rather than 24-70 and use the FTZII for the Tamron and you will be covered thru 24-600. Depending on your budget, you might find a 100-400 with a TC to be a more than adequate replacement for the Tamaron and save weight. I also use a 500 PF but Native Z lenses are remarkable performers on Z cameras.

Good luck! Oh, and you might try renting first to explore your options. It turned me away from a Sony A1, just because of the feel and menu system.