I've noted some stale PRs in Fineract. As the documentation points out, it is the responsibility of the person proposing the PR to move it through the review process. There is not a group of devs sitting around waiting to review things.
I mention this, not to point fingers, but to make sure that devs who are "sending a PR" understand that this is not the end of the story. At a for-profit company, you do your work as assigned, someone else is assigned to review it, and it proceeds like that. In an open source project, it works differently. Don't assume lack of response means rejection of a PR. It may simply mean - no one saw it or didn't have time themselves to review. In that case, it's not on them, it's on you, the person making the PR. It's also not the job of the person doing a review to fix your errors. If someone takes the time to review your code, thank them, and then work on improvements. You may have to start over. So, it is also very much recommended that you start with something small and get that reviewed - it could be that you need to change your approach or have missed a major piece of work ongoing that makes your work difficult to include at the same time.