In general terms, if you can extract the private keys from a wallet, then these private keys can be imported in to the native wallet/node app of the fork coins you are interested in.
Private keys are the “spending keys” matching public keys or “addresses”; with these keys it’s possible to spend the funds in an address.
Copay is apparently an open-source project, so it should be possible to transfer private keys to fork coin’s native app.
I found this link towards that aim: https://github.com/OmniLayer/omniwallet/wiki/Finding-and-Exporting-your-private-key-from-Bitpay-Copay
To use your private keys from Copay with the native node/wallet of Bitcoin Gold (BTG), Bitcoin SV (BSV) and eCash (XEC), you will want to get these projects’ native wallet/node apps and first run them until they have downloaded their complete, distinct post-fork blockchains.
Then you may import the private keys into each of the wallet files of these coins (usually wallet.dat). Re-starting the nodes will trigger a rescan of the blockchains for transactions that pertain to the addresses in their wallets, and render your pre-fork bitcoin coins visible in the post-fork wallets of the fork coins.
Here is a link for how to import keys into a wallet (bitcoin in this example) : How do I import a private key into Bitcoin-Core?
