Importing encryption keys from TB Desktop to TB for Android

Hello, I have read this one https://support.mozilla.org/en-US/kb/openpgp-thunderbird-android-howto and I was aiming for additional detailed info on a specific step in the "Select an encryption key or create a new key" section. From Thunderbird Desktop I can already send/receive encrypted emails from a specific email account and I have exported, on my laptop, my private and public keys as well as the public keys of some contacts. On my Android phone I have Thunderbird for Android (version 14) already set up for the same email account and, in order to start using email encryption, I understood from the above link that I first need to install OpenKeychain and then, from the image in step 2 of "Select an encryption key or create a new key" and from the text of the subsequent step 3, that I'll need to choose "I already have a key. Import end-to-end key from other device" and then, if I got it right, try to find the keys which I exported on my laptop from Thunderbird Desktop. Are there any precise details on how to find those exported keys and load them into OpenKeychain? Meaning, for instance, do I need to copy/paste the keys from my laptop into the archive of my Android phone and then direct Thunderbird/OpenKeychain to that location to pick them up? Any type of details/links/docs/videos with respect to this, will be useful. As well as any explanations in case I understood wrongly and what I am trying to do is not the proper way to proceed. Please note: I am not an expert. Thank you Best Regards