Best materials to seal curved shower wall corner to shower tray
You might try a flexible plastic "caulking strip":



I have used this several times and will share what I think are keys to success:


remove all the old strips and all the old caulking. Caulking removal is not easy and IMO is best accomplished using mechanical means (cutting and scraping) combined with chemical means (caulking remover). This takes time because the caulking remover needs time to soften the old caulk.
Thoroughly dry the entire cleaned area and waterproof the gap between pan and surround before covering it with any trim. This means caulking the gap, it's important because it will prevent water intrusion when (not if) the trim inevitably fails again over time. I won't go into detail about best practice for caulking, there is already substantial info. about that on this (and other) sites.
apply decorative trim. I suggest the caulking strip because it can accommodate curves of reasonable radii. It comes in many widths and colors, with matching widths on both sides of the fold or with narrow x wide configurations. I have found that warming it up a bit (let it sit in the sun for a while) prior to installation facilitates the process.