If the exported file contains the private key then when you import it to a new machine, you will get your original wallet and funds.
If you only have the public key, you will only be able to view the addresses, not spend the funds.
If you set "true" to private arguments of listdescriptors command then private keys are also exported, and after importing relevant discriptors you will be able to spend funds. So, achow101 response has covered your question. In modern wallet architecture listdescriptors true and importdescriptors act as replacements for the dumpprivkey and importprivkey commands used in legacy wallets.