Creating an isometric/hex-based game system

I wanna make a 2D grid-based game where you can move your units through the grid tiles. Something like FFT, and most strategy games. Either hexagons or isometric, not sure yet. It would require things like clicking tiles to deploy units, clicking these units to show available paths based on their movement range (by highlighting nearby tiles), snapping everything to the center of the tiles, that kind of thing.

By coding a grid system myself, I can asign each tile to a space in a 2d matrix, which sounds pretty nice. I can have each tile as a gameobject, which is nice, cause I want to store certain properties and logic for each tile type. I'm not sure if this is the correct thing to do, though. Desigining a map sounds really difficult like this, and I cant see the tiles until I run the game - and worst of all, I'm not sure if this is the standard, correct way to do it. Doing it with squares is easy, but hexagons and isometric games make it way harder to deal with, also.

On the other hand, I could use tilemaps and fix those issues, right? The problem is that tilemaps are just sprites, not gameobjects. So I cant customize my tiles in any way, which sounds terrible. I've heard of a few workarounds, but honestly, they sound way too complicated and unnecessary.

I'm asking for a very common thing, just a grid system - there must be a standard, easy way to do it. I've watched and read so many guides, but none of them cover for these problems... I'm really stressed having researched this so much in the past 24h, and I'm still completely lost. Please, enlighten me.

Thanks a lot in advance!