A couple of people have offered good advice. Keep in mind one main point, filling a pen through the nib is critical to maintaining proper ink flow through the tiny channel(s) of the feed. Those channels can become clogged over time with certain inks, especially if ink is not forced through them periodically. The alternative is to remove the nib assembly and force water or ammonia through the nib assembly/feed with a bulb syringe.
There are syringe filled pens. They hold a lot of ink and require a different protocol for making sure the feed is maintained.
One aspect to filling a fountain pen is the "ritual." It forces you to slow down, appreciate the mechanism you're holding and wear those ink stains on your fingers like a badge of honor. You could use latex gloves if stained fingers are not an option. Someone mentioned getting a piston filler pen. That is my preference, but the advantage of a converter is that it's much less expensive to replace a converter that fails than to fix a piston.
That being said, it usually takes a long time for a piston to fail, if ever. A little bit of dielectric silicone compound, judiciously applied every other year or so can go a long way in maintaining proper function of a piston. It's also good for helping threaded joints maintain a strong seal. I prefer a piston over a converter in part due to capacity. You'll find you have to refill less frequently using a piston filler pen. I own both and generally prefer the piston pens, although some of my converter filler pens are quite compelling.
So, if you bypass filling through the nib, you'll need to find another way of maintaining your feed to prevent a clog from developing.
The most important thing if for you to develop a system and find what works for you. Enjoy this wonderful adventure!