If you found a 2013 wallet with some coins, what would be the best method to make it usable? Im using Debian and I want to compile Bitcoin Core, sync the full node, and have 2 laptops, one for the cold storage (airgap) and one for the online node to broadcast. I want to use the new psbt method, but I don't know how to select specific utxos in Coin Control and put it into a psbt file.

Anyway, how do you do this without screwing up the wallet.dat file? There has been so much stuff added to Bitcoin Core, some of it questionable if necessary since I like simplicity and quality of life features like the mentioned Coin Control, but I think a lot of clutter was added, and now the wallets are not backwards compatible without doing some dodgy conversion thing. Please explain step by step to guarantee no possibility of screwing (wallet backup already done)