Yes, I believe that our main point of contention lie in definitions (regarding extreme ethno-Nationalism and Fascism). I agree that Manifest destiny and Lebensraum are both good analogies to Zionist policy towards Gaza. I also agree to a certain extent that there are shocking parallels between Israel's actions in Gaza and Nazi plans for Eastern Europe, but as of today, I don't think Israeli actions have reached anywhere close to the worst crimes perpetuated by the Nazis. It is a great and extremely sad irony that the, "solution," to one genocide is on the verge of giving rise to another genocide. Likewise, I don't think the solution to the current problem should involve what sounds awfully close to yet another genocide (erasure of Israel from the map). A two-state solution is the most fair long-term solution I can think of. The priority is to prevent genocide, and if a two-state solution cannot be reached, the next best solution may just have to be moving the Palestinian population to neighboring countries (which would be neither just nor fair, but would at least save the Palestinian people). Yes, it would be just as justified to, for instance, move the Israeli people to a safe haven like the United States, but I don't think that scenario has any realistic chance of occurring in the foreseeable future. Israel may be opposed to a two-state solution, but there is absolutely no way Israel would accept any form of one-state solution outside of Israel having complete control over Gaza and the Palestinians either gone or completely subjugated.
Formation of a single state that gives equal rights to all its citizens is neither a genocide nor "erasure of Israel from the map".
In regard to a potential 2 state solution, and reasoning about how Israel will have a hard time invading the Palestinian state;
1. Israel doesn't and hasn't cared about international backlash which there has been plenty of because it is backed, funded and armed by US and western powers. If you have the backing of the most powerful state, international backlash is moot. (see, banning news orgs, bombing aid, aid workers, relief workers, journalists, hospitals etc etc)
2. Israel hasn't followed UN mandates or any mandates for that matter, instead they say that UN has been infiltrated by antisemites and hamas. Again, US seems eager to discredit the UN and the Security Council in Israels' behalf as demonstrated by their insistence that Security Council decisions are nonbinding, threatening to and defunding UN organizations, going against ICC & ICJ decisions etc etc.
3. You agree that Israelis make lebensraum-esque claim to the lands the Palestinians currently occupy, their desire for sovereignty over that land will not diminish just because of a formation of a second state.
Unless there's some international coalition defending the Palestinians and keeping peace I do not trust the Israelis to somehow give Palestinians a state all of a sudden, which they've never seemed keen on in the first place.
Ethnic cleansing Palestinians from their land in some faux-humanitarian attempt to save the Palestinian peoples will embolden not only Israeli ethno-nationalists by handing them what they want, but other ethno-nationalists will realize that a killing project with genocidal intent is an internationally approved method of ethnic cleansing!
If we agree that Israelis are intent on genociding the Palestinians, which is internationally recognized as "the crime of all crimes" the solution isn't to give them what they want but to PUNISH them.