Hey there! Someone without a prostate here that is happy to talk about my experience.
So truth be told, I had never been that into anal, but I also was coaxed into by a partner who didn’t do any warmup or use lube, so yeah, not a great introduction! I enjoy it more now, but it took a bit of trial and error to find what I like, so happy to talk about that.
Inserting a finger is a great way to test the waters, but in the shower might not be the best way to do so, because 1. water can wash away lube 2. you gotta use lube for any anal play if you aren’t already. The anus doesn’t lubricate, so lube is essential. I like using water based lube, just because it’s good with safety for toys, but if you’re just using a finger you have options. Make sure your nails are trimmed and you don’t have any hangnails, because even a small snag can hurt inside, I’ve had that happen and it doesn’t feel great. I like to use finger cots (like finger condoms) with finger stuff because of that and also for easier cleanup too. I prefer a plug just to be safe and not have to worry about my nails.
As for feeling, yup, at first it kinda feels like the pressure of a BM as you enter. That’s why warming up helps a lot to relax the muscles and your body so that feeling isn’t intense. Massaging around your anus, with a finger or a plug, gently pushing on it but not inserting something yet, doing all that while masturbating can help relax your body. Also position can help. For solo anal play, some folks like to lay on their side, it can be easier for access.
I also think every body is different. A lot of folks like anal because the feeling of fullness, so they like to just wear a plug during other play. A lot of folks like in and out motion and/or vibrations. I’ll admit, it’s not my favorite activity and not something I personally find myself wanting to do alone a lot, but I do like the feeling of fullness with a partner, especially with double penetration, either with a toy in my anus or vagina. So I’m a fan of that more so than in and out movement. It’s just a different feeling and for me makes orgasms more intense because it’s another level of stimulation.
We do have a whole section of toys for beginners for anal play, lots of more slim and affordable plugs that would be great for testing out the waters!