Quote from: ChapInRed on Today at 09:45:13 AM

I have a Raspberry Pi 4 with 8gb ram which could do this, using a fresh Ubuntu install. Can I copy the blockchain files (not wallet!) from my offline installation of Bitcoin core to save me some time? That way it would only have a few days worth of blockhain to update.

I have tried to copy the whole data directory before to circumvent another initial block download and it's indeed possible.
But that test included the wallet file, I haven't tried it without the wallets. (other users may have tested it)

If it didn't work out for you, try to -reindex and see if it can fix any issue that you might encounter.

Quote from: ChapInRed on Today at 09:45:13 AM

Would I be wise to run this over Tor or is that overcomplicating it?

That's a good option for better privacy, setting it up isn't too complicated either: https://github.com/bitcoin/bitcoin/blob/master/doc/tor.md

Quote from: ChapInRed on Today at 09:45:13 AM

Finally, once Ledger set up, is there any risk/implications in transferring a test amount (like 1 to 10 mBTC) so I can get the hang of things?

Aside from LoyceV's concern above about how your old wallet.dat will handle the change, I can't think of anything else.

The procedure ensures that the unconfirmed transaction will be saved in your mempool and wallet.
So if you need to spend the change, Bitcoin Core can refer to it as long as the setting "Spend unconfirmed change" is enabled.