We're not going to lie. One of the key places people ask you for help with a PH launch is in LinkedIn DMs (followed by X and email).
Most connections I got were people from Product Hunt, so it is a pity not to use that platform. I am trying to grow LinkedIn and play with many strategies, among:
posting several pieces of content per day
actively comment on other people's posts
send a certain number of connection requests per day
In the last week, I was restricted twice on LinkedIn (where I have a community of more than 8k+ people) (the first time for 48 hours, the second time for 72 hours).