That's a beautiful shot!
My wife does portrait photography. She is typically unwilling to spend what she should on technology. She got by with a 2010 mid-range 27" iMac upgraded to 16 GB of ram for 10 years. We got her a 2019 27" iMac, but it is plagued by having a Fusion Drive, which makes it slower than it needs to be. I got her a base model 8/256 M1 MacBook Air for use in her pre-k classroom, and she has actually been using it more for photography work than the iMac these days. Naturally, she constantly has an external SSD attached to the Air.
That M1 Air is far from what I would have recommended for her photography work. She regularly batch edits dozens of images at a time in Lightroom and Photoshop, and no longer has to walk away from the machine when running groups of actions. It has sped up her process significantly, even though it is far from the correct machine.
For still photography, I'm not convinced that you need to jump to the M2pro or M3pro level CPU, especially if it doesn't fit the budget. With the Adobe suite, you can never have enough ram. I'm pretty sure I could give my wife a Mac Pro with 1.5TB of ram and she would still make it swap. That said, a fast SSD really helps when you do swap or use a lot of scratch space. If I were to get her a mini today, I would look at the M2 or M3, bump the ram to 24GB (16GB at minimum), and at least 1TB internal storage. Then I would make sure she had a reliable network attached storage system and a reasonably fast external SSD to use for scratch space. A thunderbolt enclosure for the scratch disk would be nice, but I'm not convinced that it would save enough time during most operations to justify its expense. Just getting away from a system that uses a spinning HDD as part of the central storage will be a massive improvement.