I would have to compare the costs to repair vs. replacing it. If you do want to repair it, I found this tutorial that could help you: https://www.sagecottagearchitects.com/diy-bathtub-refinishing/
Hi Grandma, Here's a how to video to paint your fiberglass: https://www.youtube.com/watch?v=vAphIbb8IjY
You can check out this post, too, if you're looking to paint. It's a big job, but it does work from what I've seen. https://www.hometalk.com/11633413/paint-your-bathtub
Depending on how much you want to spend, you could call BathFitters or someone similar and see about the tub and shower liners. They are more substantial than fiberglass and less mess than replacing everything. It's done in a day. I had an old cast iron tub that was dull and stained and did this. I had tried reglazing the tub myself and it didn't last. I'm a huge do it yourselfer and I gave up trying to make something pretty that just wouldn't stand up to the use.