I'm running an 800 GB Photos library on a Late 2013 iMac with a 3.2 GHz Quad-Core Intel Core i5 and 16 GB RAM. It used to have a Fusion Drive, but now it's running on HDD-only (why pay to replace the SSD in a machine this old?). I can't say anything I do with it runs well, but Photos runs no worse than anything else. So to me the question posed here seems ludicrous. Of course, M1 or M2, 13-inch or 14-inch, MBA or MBP, 8/16/24 GB RAM... any of those is going to be far and away more capable than any 8-year-old laptop.
You're not talking about a pro photo/video editing app with minimum configuration requirements that are higher than an entry-level computer. You're talking about Photos, which is designed to run well on any Mac.
Will the system be, "...strained when I organize and scroll through/enjoy my oversized Apple Photos library?" The size of the library is not material - most of that space is dedicated to the full-size images, and the only time full-size images load is when you are actively viewing/working on them - one at a time. When scrolling through the library or organizing albums it is loading just the lower-res preview images. The vast, vast majority of the library's contents are not touched by those processes. Organizing contents simply updates database records. So just discard any notion that library size has any bearing on system performance, so long as there's enough SSD space to hold it. Do you actually need 2 TB when your current library is 300 GB? If you have the guts to actually hit "Delete" on the worst/most useless outtakes of a shoot, who knows how long it will take to fill 2 TB? Of course, video professionals are going to accumulate far more than 2 TB, but they don't keep all their years of work on an internal HD, they have strategies for storing old projects elsewhere.
Trimming/stitching together 5K videos? In Photos? Trimming, yes, "stitching together?" What video editor are you using? There are certainly resource-heavy tasks in photo and video editing, but you haven't named any that you are using. Well, other than focus-stacking of stills.
Overall, a lot of us over-estimate the demands we place on our computers. We impress ourselves with the supposed sophistication of the way we work or play with our machines and think that only the biggest, fastest, most over-spec'ed hardware will do. In reality, many of us barely scratch the surface of what our machines could be capable of. Open and learn how to interpret the information provided by Activity Monitor. Then do your work/play, watch the CPU Load and Memory Pressure graphs, and see just how hard your system is really working.
By all means, buy as much new Mac as you can afford. Bigger is always better. Why transport a week's worth of groceries in a subcompact when you can carry them around in a full-size SUV?
