Your reply has been heartwarming (and you're right, I'm not technical enough to understand the detailed workings of transactions). So, after spending a few more hours on this I managed to feed the BTG signer with the correct data. Problem solved, thank you!

Does it mean that by using an P2SH-P2PK address I indissolubly and irrecoverably bound my chances to recover forked funds to the fate of Armory?

No way to do this via methods similar to what is described here https://www.reddit.com/r/BitcoinAirdrops/comments/7io9d4/guide_retrieving_bitcoin_gold_from_segwit_address/ or here https://bitcointalk.org/index.php?topic=2689834.msg27503623#msg27503623?

Hi,

I'd like to copy an address from my Armory wallet, displayed under the section P2SH-P2PK, to a Bitcoin Core wallet, along with the key required to sign a payment. Is this possible? If not, are there any wallets that are able to digest Armory's data to that end?

Thank you very much in advance!

Kora