I'm sure lots of lovely women will come your way with much better advice than I can give, but! I think the first thing is that you shouldn't be shy or embaressed looking at this stuff yourself. You know your own body the best, trust your gut!
There are so many different places you can see and buy toys, even Amazon (probably best to avoid places like Temu/Wish because poor quality materials can be bad!).
Maybe try figuring out what your current limits are? The great thing about fingers is you can use more or less so it's easy to figure our how wide is too wide, and we'll as for depth? Well just because you have a 10 inch toy for example doesn't mean you have to use all ten inches!
Try have a look around some sex toy sites like Bondara/Lovehoney or anywhere else! You can find rabbit toys, dildo, vibrators of all shapes and sizes and I'm sure it won't be hard to find one that appeals to you!