The suggestion is quite simple.
Add events in expo missions where players can get some new premium items (like newtron, kraken, boosters and so on).
For boosters... maybe kind of BP items (just 1 day of effect)?

Nice, simple idea. I like it
Would be best if the boosters last for no longer than 1 day.
I guess the possibility of finding a bronze/silver/golden booster goes with same chances as other at events? I thought it was +- 90%/9%/1%?

Nice idea.

I think that this idea bring some activity back to the Ogame universums.

Yes... expo missions... so missions sent to x:xxx:16 system position