Is there a way to import a reading list from a manga site like MangaDex or Comick or whatever else to Manga Updates? If not, could we possibly get one please? It would be very useful.

There is not, also mangadex doesn’t allow to export reading lists directly so users need to get an API key then either:

1. (if the process runs server-side) share it with a 3rd party or
2. (if the process runs client-side) must have a powerful device or wait a while.

Personally, I wouldn't add a feature like this to my website, at least not officially. But It won’t be very complicated because most of the series on Mangadex (and so Comick, they steal info and chapters from Mangadex) have Mangaupdates ID.

How I know that? Because I’m thinking of making a multi-platform manga tracking app for myself one day.

Quote from m.a.tecik (and so Comick, they steal info and chapters from Mangadex) have Mangaupdates ID.

According to the dev from Comick he takes the info for any manga from right here, I've no clue about chapters though or how they handle that. I was mostly asking as I've a memory of back around when Batoto died or perhaps even earlier I managed to save my reading list from there and brought it over here so I wouldn't lose it. Oh well, thanks for the reply.