Plausibility Check: Balkanize Ottomans pre-1500?

So I hinted at a possible crusade against post-Interregnum Ottomans under Mehmed I (also before his OTL death in 1421) at the end of my last chapter in my back-from-the-dead TL.

I'm wondering about the possibility of the Ottomans, weakened by a 'brothers' war', pitting countrymen against countrymen, and agitation by local populist rebels, losing their holdings in Europe altogether as a result of a massively-successful crusade led by HRE Sigismund von Luxembourg, Ladislaus of Naples, and the Teutonic Order. Is it a fallacy to suggest, not only that the crusaders would enjoy a high level of success, assuming 'adequate' organization and leadership (i.e.: none of the in-fighting or other blunders that led to the disaster at Nicopolis), but also succeed in seizing and divvying up Ottoman Europe, however that may be done?

I'm worried it will be viewed as pressing the 'balkanize now!' button. I don't mean to 'remove kebab' or restore Byzantium or anything like that. Just looking at this as a possible, natural consequence of a stronger HRE, Naples, Venice, Order-State, etc., which is what I've got in my TL so far. Also, the papacy is still controlled by the Avignon candidate, Benedict XIII, now restored to Rome and protected by Ladislaus---would he not also want to assert himself and 'do something' about the Turks while they're weak?

Please submit your questions and concerns; I really need this feedback before I continue work on my next chapter.
 
150 and still nothing?

What is the plausibility of, say, specifically, Serbia expanding their OTL 1410-ish borders, Wallachia seizing Dobrogea, Venice expanding significantly in Greece, and Bulgaria getting independence?
 
I did mention Ladislao. Please give my timeline a read? It explains the unlikely circumstances far better than any summary I can give.

I aim to put a Catholic on the eventual Bulgarian throne, but we'll see.

Ladislao and Sigismund are congenial rivals, more or less. Mutual respect rather than bitter enmity. Hussites are butterflied away, and Sigismund was elected king of Poland. France is busy with England and Burgundy. Ottomans are ripe for crusading, the time is right.

Just concerned that having a crusade force them out of Europe will not be met well.
 
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