Affinity Publisher seems not too different from PagePlus in its use so should not be too difficult to learn.
However, I have been using PagePlus since the 1990s, currently on X9 which is excellent and more stable than its predecessors, and consequently I have created thousands of ppp files - single page posters, numbered event tickets, merged membership cards, small publications (up to 44 page booklets), etc. All done without charge for various small local and national organisations and charities. I use many of these ppp files as templates for new work so not being able to open them directly in Affinity Publisher is quite a blow. Yes the pdf route sort of works but the result takes a lot of editing time to achieve my original layout, especially where I have applied a lot of effects which seem to come out as curves in AP rather than text. If Affinity could support the import of ppp files more faithfully I'm sure it would attract many more PP users but for now I will probably use it only for brand-new work and stick to PP for my regular work.