There is no doubt more to say, but the always excellent u/commiespaceinvader provided a very full response to this question in an earlier reply, which you might like to review while you wait for fresh answers to your question. There were many follow-ups, so do work down the whole thread:

What were Nazi plans for their own soldiers who were disabled or mentally handicapped from war?

In addition to the link posted by u/MikeDash, the same user, u/CommieSpaceInvader, gave a detailed reply to my own asking of a similar question about 3 months ago. This one might have more info/development compared to the 6y old response, but both are doubtlessly worth a read.