GG.Deals doesn't offer an export function, and Backloggd has it on their public roadmap. In the meantime, you can try importing a text list.

Import from HowLongToBeat


We bring your scores and even the time you logged, following the format they provide.
However, games must be matched by name, which means a few of them might not link properly. Please check the outcome.

1. Sign in to HowLongToBeat
Make sure you're signed in at howlongtobeat.com before continuing.

2. Open your Options page
It's right under your username, top right.

3. Export your games
Manage Game Lists section near the bottom → All Playthrough Data.

4. Upload the file here
and check the results

Done? Check your profile and playlist