So who's won at the end? Gyuri or fromis_9?

Gyuri ultimately chose to leave the group to pursue her acting career.

Meanwhile, fromis_9 has been appearing on shows, having concerts, etc.

Gyuri's drama is close to ending as of now, so who's won? Did Gyuri make the right decision to focus on her solo career at this point in time, 5 years into their careers?

Gyuri did. It was a good time to leave. She's had idol experiences, went on another survival show and really got her name out there. Now, she can get a headstart and focus on acting, which is a much better career path long term.

Look at how other idols who's overstayed their welcome as idols like Gfriend. Individually, they have little to no recognition and their actress like Sowon is forced to work on no-name projects and dramas that no one except their fans is watching (bit harsh but let's be honest now), despite Gfriend being one of the mid-top tier girl groups of 3rd gen.

Gyuri was interested in acting and made a good decision of leaving fromis. Because while staying in the group it wouldn't be possible to pursue acting career.

Gyuri does seem to have acting skills, not all idols have that.