Can I import private key into another wallet service?

I’ve been having problems with my current cold wallet. I can’t seem to get my coins out of the zaddr.

I was wondering if it there could be any wallet software or online service that would accept my wallet.dat or private key? Could this be a way for me to retrieve all my coins if I do that?

Thanks in advance!

Yes, there are wallets like Zcash4win, Zcash4mac, the Zcash Linux client will allow you to import the private keys.