OpenOffice is dead since years, Libreoffice is what is used today :D
Btw Inkscape is said to be quite good. GIMP 3.0 will have color profiles and nondestructive filters.
I used Libreoffice Impress instead of Powerpoint recently.
you will need to learn the core concepts new, master slides etc.
once you have your own templates, presentations will be very nice
you dont get AI bullshit templates so more manual work but more authentic presentations
same for hunting down icons, stock images etc.
for collaborating OnlyOffice is used, integrated into Nextcloud. OnlyOffice has a Desktop Client, but I dont see the reason, Libreoffice is more feature complete.