My heart goes out to you, your brother and family. There’s nothing more distressing than seeing a loved one suffer and not be able to offer comfort. I hope he’s able to find a compatible blood source soon to help boost his hemoglobin while waiting to find a long term solution for his failing health.
I did a search through our forum for references to splenectomy for anemia and found only one entry with @ngm01 in this discussion: https://connect.mayoclinic.org/comment/766994/

His situation wasn’t the same as your brother’s but perhaps he can share his experience after the splenectomy.

There are other references to splenomegaly and splenectomies but not in relation to CDA type 2 anemia, they’re more cancer related. If you’d like to read through some of them, choose your topic such as splenomegaly or splenectomy, or splenectomy for anemia, etc., in the top search bar and all the conversations will show up for you.

I’m sorry I can’t be of more help to you in finding answers. I’m hoping others will see your post and jump into the conversation with information that would be useful to help your brother.
You’re a wonderfully thoughtful brother and I wish only positive news for your brother. Will you keep in touch to let me know how he’s doing, please?