1. What does it mean?
포꾸 abbreviates 포토카드 꾸미기. It is the craft activity of styling a photocard display, sleeve, or holder with stickers and other decorations. In fandom conversation the focus is making a card look personal and attractive.
Also written or said as pokku
2. The nuance
People often decorate a protective layer instead of the original collectible. It overlaps with 탑꾸, which specifically focuses on a rigid top-loader holder.
3. Examples
“포꾸하려고 작은 별 스티커를 샀어.”
I bought little star stickers to decorate my photocard display.
“카드에는 안 붙이고 겉면만 포꾸했어.”
I decorated only the outer cover, without sticking anything on the card.
Sources
References support the meaning and usage. Example sentences are written for NoCapWiki.