Throw it out?
They are not unrepairable. Nor are the un-upgradeable. What gave you that idea?
The LCD panel can be replaced in about 45 minutes. . . Also the rear case is removable to access the components. Someone is blowing smoke about it not being serviceable. The RAM is not soldered to the logic board. It's standard SDRAM Look at the photo showing the replaceable RAM, SSD, and even the the graphic card, although not showing in the photo below, can be swapped out. I'd guess it's likely not intended to be a user task to do any of that, but it is doable for anyone who is not afraid to do technical work.
iMac Pro with back case removed showing components.In addition, I've been managing iMacs for almost 20 years and have had over one hundred go through our office. Of those more than one hundred, only one has had an LCD panel fail, and it was over seven years old when the lower backlight quit. It was time to retire that iMac anyway so we sold it to someone who was willing to open it up and replace the backlight Florescent bulb, a $10 component. He did. Used it for three more years until the logic board failed at ten years old.
Even the latest model iMacs are accessible through the screen. . . and are repairable. You just have to know how. It's actually fairly easy once you've done it. You DO have to have a re-assembly kit from Apple to put them back together that includes an adhesive double-sided gasket. But, again, once you know how, easy.