In that case you may not have to export the private key at all. Try this guide instead but substitute 'ETC' for 'UBQ', except in step 9 I believe you need to select the ETH address you sent the UBQ to.
https://ledger.zendesk.com/hc/en-us/articles/115005200029-I-sent-ETC-on-an-ETH-address-how-can-I-recover-them-1. Connect you Ledger device, enter your PIN code, enter your Ethereum application and disable the browser support setting
2. On your Ledger Wallet Ethereum application, copy your ETC UBQ address // Please verify twice that it is the ETC UBQ address, not the ETH one.
3. On your Ledger device, enable the browser support setting
4. Go to MyEtherWallet website (not the Chrome extension plugin)
5. Select "ETC" "UBQ" in the top right menu
6. Select the "Send Ether" tab
7. Select the "Ledger Nano S" option and click on "Connect your Ledger Wallet"
8. Select the " m/44'/60'/0''" derivation path (Ledger ETH)
9. Select the address where your ETC UBQ are. If you don't find the right address, don't forget to click on "More addresses"
10. Click on "Unlock your wallet" to display the wallet manager
11. Paste your ETC UBQ address in the required field and empty your account
Unfortunatly i tried this but etc and eth are on the same "aplication" on the device this is probably why you can do this. In the case of ubiq it's an other app that you have to open.
So it seems that the best solution was to import the eth private key on the ubq app. But if it's easy to get the private key (thanks for the answer) that's an other things to import it.
Well if you have a clue i m around. If not thanks a lot anyway for your time.
I have send a request to the autor of the support article that you give me. Now finger crossed