The TVöD table is used only for state jobs, as far as I understand. Can this table be used as reference for realistic salary expectations (as a Software Developer) or is it way too high or way too low compared to the actual average salaries?
There are job postings for software developers in public service, and they are usually in the E10..E12 range. But I'd say it's a bit low compared to industry, and some of those postings even say that they are willing to pay a bit more ("Zulage").
You could also compare this to IG Metall, which is quite a bit higher for the same levels, and has increased more in the last twenty years. A software developer would be in the EG 11..13 level in IG Metall, AFAIK.