I’m going to split this suggestion into two, one that I’d seriously consider and one that would be nice but would also never happen.
My serious idea would be to add a PVAL (platform validator) on the Platform 2/3 island at Fratton, which would be useful for passengers entering the station with smartcards from the Goldsmith Avenue side of the public footbridge (the one on the west side of the station).
The Selbourne Terrace side of the footbridge has a PVAL at the bottom, but if you’re coming from Platforms 2/3 wanting the Goldsmith Avenue side of the footbridge and need to validate your smartcard, you’d need to head up the bridge and back down again to Platform 1 (or the PVAL on the other side of the footbridge), tap on the PVAL there, and head back up the footbridge to exit the station.
With the new PVAL on the Platform 2/3 island, you can simply tap out and exit the station.
Of course, the issue with this is it would only really be useful on Sundays (or other times when the gateline is unstaffed) when the footbridge gates are open as the gateline is unstaffed (and therefore also open).
When the gateline is staffed, passengers arriving on Platforms 2/3 walking onto Goldsmith Avenue have to walk in the opposite direction to the direct footbridge, walk over the other footbridge to Platform 1, pass through the gateline, walk down the road to the footbridge that they looked away from earlier, then use that footbridge to make their way over back to the main road.
If you were to really start getting out the crayons, of course you can’t just keep the footbridge gates open when the gateline is staffed as that would defeat the point of the gateline.
I’d propose extending the main footbridge (the one on the east side) onto a new entrance building at Goldsmith Avenue, with a remotely controlled gateline, lift and a few ticket machines. Fratton station has quite a large catchment area, and would be useful for anyone continuing their journey to the Milton and Eastney areas.
This does however come with the caveat of compulsory purchase of the goods yard on the main road in order to build the second entrance.