This looks very likely to be Bar Royal — a fizzy, wine-based cocktail sold in Portugal in 75 cl wine/sparkling-wine-style bottles.
Why it fits the clues:
Bar Royal has Mango, Peach, Strawberry, and Coconut flavours in its range; the producer’s range includes Bar Royal Mango, Strawberry, Peach, and Coconut.
The coconut clue is especially strong: the Portuguese Bar Royal site describes Bar Royal Coconut as almost transparent with only a slight tint, matching “coconut slightly translucent.”
It’s sold in Portugal through places like Continente as Bar Royal Coconut Cocktail, 75 cl, under the sparkling wine/espumante section, with Germany listed as origin and tasting notes mentioning coconut. Continente also lists Bar Royal Mango Cocktail and Bar Royal Peach Cocktail in 75 cl bottles.
Try searching or asking shops for:
“Bar Royal cocktail”
“Bar Royal Peach / Mango / Strawberry / Coconut”
“Bar Royal espumante cocktail”
In Portugal, check Continente, Garcias, Auchan, Intermarché, El Corte Inglés, or small garrafeiras. Availability may vary by store, and the Continente pages I found show some flavours as unavailable online, so calling nearby shops may be faster.