To get the legacy public wallet from the private key I used the old brainwallet javascript web site. Know of any javascript sites that work offline to calculate the segwit address from the private key?
https://kimbatt.github.io/btc-address-generator/?page=address-detailsIs the actual page you need, you can go to
https://github.com/Kimbatt/btc-address-generator to download the files and run then offline.
--> I have used this on and off for the last few months to test things but I have not verified / check the code at all so make 100% sure you are 100% offline when using it and purge everything from your browser when done.
The other option is to run electrum while offline and import the key, you should see the address. Then shutdown electrum and delete the wallet.
-Dave