Since you say it is a lot of bitcoin...

Electrum is the way to go.  Not Mycelium or another mobile wallet.

Here is a very high-level overview of the steps:

Creating the sweep transaction (online)

• Setup the hardware wallet (backup the seed, etc)
• Record the hardware wallet address it generated.
• Load the paper wallet address into an online version of Electrum (Keep the private key away from that computer, just the ADDRESS)
• Create a tx spending from the paper wallet address to the hardware wallet address.
• Save the tx as a file to a USB stick.

Signing the transaction (offline)

• Create a secure TailsOS on a second USB stick and boot into it. (make sure to select Networking => Offline from the welcome screen)
• Load Electrum (it is pre-installed)
• Create a new wallet from your private key (type the whole thing)
• Import the unsigned tx and sign it with your private key
• Save the signed transaction as a file back to the USB stick

Broadcast the signed transaction (online)

• Rebot back to your online system
• Load the signed transaction into Electrum
• Broadcast it