Shaking lulav during hallel
I grew up in a shul here in Canada where the entire congregation shakes the arbah minim by the first two hodus (while the chazzan does the first hodu and yomar na). I haven’t found a source for this, as the mechaber (651:8) says to do only once and the rema says for all four. Even the rema who adds that the minhag is for the chazzan to shake by the first two only said so according to his minhag that the kehilla shakes by all four. I mentioned this to the rav, but he isn’t willing to budge since “this is the minhag”. To me, it is a minhag to’us, but perhaps there is a source for this. Is there?
I am unaware of any source that requires the tzibbur to shake by the first 2 of the hodus, rather as you mention either by one or by all 4.