I have read that Palestinians supported the Islamists in Egypt, and for this reason Egypt today will not be keen to accept any Palestinians. Is this true?
To be honest, it's been a while since 2013 now so I can't recall the full specifics of positions etc.
Having originated from the MB, Sisi was obviously inherently hostile to Hamas.
There's also a desire to link almost any terrorist activity in Egypt to the MB, directly or indirectly and therefore Hamas by extension.
Also some ridiculous conspiracy theories by the regime supporters about Hamas (and Hezbollah) being involved in prison breaks in Egypt.
They have worked together however since 2013 to root out salafi jihadi elements in the Sinai.
I can't speak for all the countries and people of course but my experience has always been that Arab people are far more supportive of the Palestinian cause generally than their governments.
There's lots of reasons I think why Arab countries don't necessarily take on loads of refugees now. Firstly, as I said, they already have millions of Palestinians among their ranks. Secondly, there is a fear that like the 1940s, if they leave, Israel will not allow them to go back. Thirdly, there may also potentially be a fear that a large influx of them may also come with elements of Hamas/PIJ and the Israeli response that could accompany this.