It's hard to prove that striking a villager with a net or complaining to Isabelle about said villager actually prompts them to move out any earlier, so I'm not going to comment on that method, but this is what I do know from time travelling for months at a time:
Ignoring a villager has no effect on when they choose to move out, or at least such a minor effect, that it's an unreliable method. I have ignored my villagers for 5~ months at a time and each time I cycle into my town after forwarding my date, one of those villagers, whom I've deprived of attention will have a thought bubble over their head asking me to move out.
What's interesting is that I have found that unlike New Leaf, this game disallows villagers from moving out if you time travel far in advance without checking on your villagers. In other words, villagers don't move away if you haven't been on in weeks/months. They will instead have a thought bubble over their head whenever you log in next. This is a fantastic change, imo.
Basically, the fastest way to get villagers out, barring amiibo, is to time travel a decently long time ahead and check to see who has the thought bubble. Personally, I travel ahead a month at a time and I typically find a villager asking me to move out everytime I load my island.
And if you ignore them, they’re actually less likely to move when you want because you have to start the whole “oh i haven’t talked to you in ages” dialogue which holds you up.
This doesn't change anything, as you don't have to actually speak to any of the villagers when you want to check if they're moving out. Look above their heads for the thought bubble, or if they do not have one (as the bubble does disappear after a few seconds of them being in sight of your character) then they'll still have that, uh, thinking pose? that they have when the thought bubble is there. The pose also signifies they're thinking of moving.
