News-Pipelines and the proposals repo is for full pipelines.
Like Georgia says, you normally don't have to ask before you make modules unless you think the tool/module design will violate the nf-core specifications and you need an exception.
The only normal 'filter' is like Georgia says - checking the modules do not already exist on issues/pr/modules repo. If not, make an issue, assign yourself and you can start working.
If you thinkt he module violates the specifications, then describe the problem with the tool on #CJRH30T6V and we can discuss there