But you shouldn't be exporting individual private keys anyways. The wallet does not use just one private key, so having an individual child private key is really not that useful.
I can think of something: I once needed to (quickly) use CPFP, but Bitcoin Core's GUI didn't allow me to use an unconfirmed input from a third party, so I exported the private key and imported it into Electrum.
It's much much safer with descriptor wallet, something similar can be done by importing the address' parent "
extended public key" to Electrum instead and perform CPFP with it.
The PSBT transaction is compatible with Bitcoin Core, you only have to enable the necessary options if you're using the GUI: "
Settings->Options...->Wallet->Enable PSBT controls".
When importing the 'xpub' to Electrum, it should be converted to 'zpub' or 'ypub' with the command
convert_xkey to match the target script type.
Example:
convert_xkey(xkey="xpub.........",xtype="p2wpkh-p2sh") or
convert_xkey(xkey="xpub.........",xtype="p2wpkh")