I would use a door bottom.

One issue I see with many of these prefab products is they're too short. All my exterior and most of my interiors doors are wider than 36".

If your wood door is exposed to any type of weather, you may want to put the storm door back on. Storm doors protect your wood doors. I wouldnt have any exterior doorway without a storm door. My storms all have pull down screens and its really nice to open the main door, latch the storm door (all mine have deadbolt locks) and pull down the screen, to get ventilation.

There is a portico over my front door so it doesn’t get exposed to the elements. We want the door to look more historic without a storm door which we don’t use. There is also not enough room on the front stoop when the storm door opens out.

Pic of house the painting is not complete yet

You may be able to replace your threshold with one with a vinyl "bulb" on top like this: https://www.lowes.com/pd/M-D-36-in-x-3-75-in-Aluminum-Door-Threshold-Install-with-Screws/3125963

Big box stores have very limited options. I got some door sweeps and a threshold from Trademark Hardware on line. I needed help with an Interior door where the furnace lived and an exterior people door from the garage. Our front entrance door seal was fine so I don't have much insight to offer for that. I phoned them. I didn't know the correct terminology to search their website. Results were perfect.