Is there any way to import photos from camera roll to Snapchat memories 'snaps' column?

You can do that in two phases:

1. Import the photo to the “My Eyes Only” section
2. Move the photo from the “My Eyes Only” to the “Snaps” section

Phase 1: Importing from the camera roll to “My Eyes Only”

1. Open Snapchat
2. Navigate to the memories screen
3. Tap on “Camera Roll”
4. Tap on the desired photo
5. Tap on “Edit & Send” or swipe up
6. Tap on the symbol with three horizontal bars (≡)
7. Tap on “Move to My Eyes Only”
8. Tap on “Move” to confirm
9. Decide what to do with the original from the camera roll
   1. Tap on “Not now” if you want to keep the photo in your camera roll
   2. Otherwise, tap on “Delete”

Phase 2: Move from “My Eyes Only” to “Snaps”

1. Tap on “My Eyes Only”
2. Enter your passcode
3. Tap on the imported photo
4. Tap on “Edit & Send” or swipe up
5. Tap on the symbol with three horizontal bars (≡)
6. Tap on “Remove from My Eyes Only”

Now this photo is available in the Snapchat memories “snaps” column.

Hope this helps!