This would be very easy to make, and, should you not find  an alternative in a satisfactory time it would be my pleasure to make it.
On a side note, you may also be able to find toys that do similar, I'll do some research and post again if I find something.

well #1, there's this little
drum machine thing here, you have a couple packs when you download and extract it and you can add more or change the existing ones. Read the read me for more info.
A piano program as well, though not sure if it functions anymore but worth a try,
I'll post if I find sometings else

This is a rather OKay time waster, though only for a few minutes. . It speaks the alphabet and plays an according sound, though be warned there is kill and zombie in there, the kill(k) key will play a sound of someone falling to the ground while saying uuuu or something and the z will play a low pitched zombie moan thing. Here it is,
File convoy file, Do not know megabites

I also figured I'd bring something different to the table. this is an online virtual piano player. It's not the best, and sometimes it lags, but maybe you'll like it or it'll be a timewaster. Once you enter the page, wait for like 5 seconds and if I'm not wrong, press ensert space(aka enter editor mode or something) and start pressing keys.
Virtual piano.

Nash Central has a full-on soundboard, though I think it requires the pressing of some modifiers to pass through to it, however, you can assign a particular key any sound, and I'd assume most of the keyboard can be used for this.

I think what we are looking for would be something that when she presses a letter would either say the letter name, or play a sound and also pop up a graphic that matches. Examples. A, apple, airplane, astronaut. B, banana, banjo. C Cow, corn, cat. etc. numbers would say the number and show it on screen. control keys or other random keys might just play random sound effects with friendly graphics. I hope this makes sense? This way she can learn while playing. I realize toys exist, but she doesn't want toys, because she realizes they aren't real. She wants to use the computer like we do. If someone could put something like this together rather easily, Sofia would be ever so greatful. I believe Lisa and Lily might like it too. 1 note, if possible make sure none of the graphics flash. Sofia has seizures and we wouldn't want to trigger those. Thank you all from the bottom of our hearts. This community has been so kind words can not describe the feelings of greatfulness and joy we feel, knowing people care.

@13 sounds simple enough.
I've started working on this and will have the letters numbers and sounds part done pretty quickly.
Bare with me while I look for pictures. Will post again with updates

Update: End of day 1. I've already coded a to z and 0 to 9. When you press these keys it announces what key you pressed. With a to z, it will randomly announce a word instead, for example: apple, bear, cow, dog.
I've tried to choose words that are quite simple and should be easy to learn. I additionally am going to gather sounds for other keys like home, end, page up and page down. I currently have a list of 39 keys that I'm looking for sounds for. My plan is to make them quite wacky, a horn, a cheer, maybe a moo, and a bark?

Even if this specific program doesn't get used by @nightshade and @nocturnus it's proving to be a fun program to make and I am curious for opinions.

Wow, its kind of awesome to see people willing to code something for such a beautiful cause, franticly it touches my heart a lot.

The link from post 8 is https://virtualpiano.net/
In the post it is missing a colon which is why it fails to load.
Fun little tool, makes me miss playing my keyboard!
HTH

Good morning!
@21 I'm going to source most sounds from free sounds if I can, mostly because I find it easy to identify their licenses and things like that.
If you have recommendations for quote unquote wacky sounds I'm definitely open.
Yeah, I'm definitely going to need some sighted assistance with pictures and I do have a few people to lean on but again recommendations again also welcome.

@Defender, Dardar and others who are contributing, thank you ever so much.  I seriously hope this does become a thing because I know Sofi would enjoy it immensely.  AS Nightshade mentioned earlier, it's just the idea of doing what Mommy and daddy do that is the real incentive here.  Someone here mentioned that touch interfaces such as iOS and Android devices would probably be better, but the problem with that idea is quite simply that while we do have them and use them to some extent, she doesn't see us using them as much as she sees us using computers.  So what does she do?  Why, climb in a computer chair and fiddle with a keyboard, then get mad at it because it's not doing something!
When she sees her sibblings using the iPad she is interested, but for the most part, that's just it.  AT this age and stage in life toddlers base themselves so heavily on what they see others doing, and since her brother and sisters are going to school and the only other people she sees regularly are using computers, she's going to want to use them as well.  This is the reason I came here and hoped someone could help out.