Is it safe to install a trusted CA certificate from another source?

As you may know, a CA certificate issued by Sectigo expired recently. This is affecting certain mobile apps and possibly websites, rendering them unable to connect to required network resources. In particular, some older devices that do not have the replacement CA certificate are unable to connect to servers using such certificates.

A work-around is possible (How can I work around the expired Sectigo certificate on my old mobile device?)… but is it safe? What dangers, if any, is a user potentially exposed to by copying a CA certificate from an already-trusted device to a device which does not have said certificate?

(For this purpose, please ignore the broader issue of whether using a device that is not receiving updates is safe. We all know that has its own risks. I am asking specifically if installing a CA certificate that is already widely trusted is any more dangerous than simply using such devices without installing the new certificate.)