There is a way to say hungrier, but my question is whether there is any way to use the same form with starve. I searched and found nothing.
I would like to know the comparative adjective of starving.
Words of two or more syllables usually don't form comparatives with -er. There are exceptions, (such as words like hungry, that end in -y) but this holds as a general rule.
When I read the title of your question, I had no idea what you meant by starvinger. In context, most people would understand it, but it certainly isn't a standard form.
You would have to use more starving, though (as KillingTime said in a comment) I don't find starving to be a concept that can be compared.
Adjectives whose inherent sense is already an intensified or extreme quality cannot normally be made into comparative and superlative degrees, nor may be they be modified by the same sorts of words you can use on regular adjectives. Sometimes these non-gradable adjectives are called extreme adjectives, strong adjectives, or even limit adjectives. (But be careful: limiting adjectives are something else altogether.)
Extreme adjectives aren’t gradable because they already mean some quality that’s as intense as possible. They’re maxed-out already; they’re super-something. For example boiling means very hot, freezing means very cold, ecstatic means very happy, starving means very hungry, spotless means very clean, and giant means very big.
So while you can say that something is very cold or that one thing is colder than another thing, you cannot really say that something is very freezing or that one thing is more freezing than another thing is. Only little children might ever say that their house was “gianter” than their neighbor’s house: we just don’t say things like that because they do not sound right to us.
Because starving people are already very hungry people, you cannot have starving people one day and more starving people the next. If you try, that more will be understood to apply not to the adjective starving but to the noun people instead. So if one country has more starving people than another one has, the first country’s people are not “more starving” people; it just means that there are more people starving in the first country than in the second.
Extreme adjectives can still take certain adverbs. You could be completely furious not very furious, or utterly spotless not very spotless, or truly starving not very starving, or entirely impossible not very impossible. Native speakers hearing these might attempt rescue readings that forced some sense into them, but it is not normal, common, or easily understood.
For most and possibly all of these, here and there you can find scattered published examples of non-gradable adjectives with a very or a more in front of them. But these are quite uncommon, and many sound “off”. For example, here’s a Google Books search for very starving showing that it does occur, albeit rather rarely. A similar search for more starving has almost nothing but false positives in it because native speakers seldom say that in the sense you intend; that is, to somehow mean “more very hungry”.
As a non-native speaker learning English, you should learn the difference between “regular” adjectives that you can grade and compare on the one and, and “extreme” adjectives that you really shouldn’t do those things with on the other.
True starvation is such a rarity in our society that we lose sight of the original meaning of starving, and simply use it to mean "intensely hungry". In that role of course it can have a comparative and superlative uses, but like most words ending with -ed or -ing, only as a compound, not by inflection.
In its true sense, starving means undergoing a privation that will lead to death if not reversed.
Comparing with a walking child, where it makes no sense to describe a child as more walking, but rather to have walked further, so one can have starved nearly to death, or only starved for a day.