Babe boot up, Raspberrypi just dropped their 16GB Pi5, for less than the price of a Cold Card! If your poor PI4 has seen better days, this might be an affordable upgrade for your node.
Honestly don't think PI's cut it anymore if you're really interested in putting your node through its paces and running other apps, but for a passive blockchain validator still a good option
https://www.raspberrypi.com/news/16gb-raspberry-pi-5-on-sale-now-at-120/