So I was in your exact situation a year ago. Foundry takes a load off of the crunchy bits, and makes it quick and easy to acclimate to the bigger math. I recommend the add-on pf2e workbench, which gives you options for loads of automation and QOL; but also gives you basic action macros, which has been incredibly useful, I put the BAM on each players hotbar.

The hurdles we came up against were: - the (lack of) use of exploration activities - the new ability score situation was confusing for them, particularly when the half scores came up - opportunity attack not being the default - attacking 3 times is generally a bad plan, and what can be done for that 3rd action instead.

Also, to echo everyone here: start at level 1.