Just because you lack the skills to fix it, doesn't mean it's not repairable. People desolder components all the time to fix phones and ipads and laptops.
Can you just fix an F1 engine with a wrench?
In fact the current Gen is bigger than the trashcan ones by quite a bit (although IIRC the trash can Macs had user replaceable SSDs and GPUs)
I totally missed that they released a new Apple Silicon Mac Pro. Turns out it has PCIe slots.