Discovered three Mac Pro (Late 2013) 8-core Xenon cans in my office that were dropped off for IT to surplus. They hadn't been used for years, replaced with iMac Pros. Pulled one can aside today, cleaned it out and did a fresh install of 'Big Sur', though does support the most recent version 'Monterey' as previously noted.
Was surprised that these Mac Pros 2013 are still as fast as my office Dell Xenon Workstation, and supports 3-5K displays. Though my Dell has faster M.2 SSD and more powerful nVidia GeForce GTX card I added. So has some advantages in media rendering speeds. But the Mac Pros 2013 are still highly usable and wondering if I should have a conversation with our property manager whether we should hold onto these. Not just dispose them.
In any case, keeping at least one can as another development box. Bonus, you don't need a separate desk heater in the winter months.