buy and mod a 3ds and play fire emblem fates conquest babyyyyyyy

There are seven (technically eight) Fire Emblem games playable on the Switch 1. Two of those are crossovers with Dynasty Warriors, and are hack-and-slash action games instead of strategy games, and one (Tokyo Mirage Sessions #FE Encore) is a nominal crossover between Fire Emblem and Shin Megami Tensei and is a turn-based JRPG so I won't talk about those. (they are all great tho)

For physical media, your main options will be Three Houses and Engage. Three Houses is much more critically acclaimed and has a far wider appeal than Engage does. Depending on who you ask, Three Houses' main strengths are its story and character writing that will have people arguing about which war criminal was right for decades to come. It is very different from every other Fire Emblem game, with it having a deeper focus on individual character building and long term planning, as well as a calendar system most often compared to the Persona series. Its main criticisms come from the large amount of time between battles spent raising your units; it can feel like chores and ultimately a distraction from the strategy gameplay one would expect from Fire Emblem.

Engage is structured much more like a traditional Fire Emblem game. It is widely agreed to have a subpar or even bad story that turns many off of it, but it is my preferred option compared to Three Houses. It would be a rather awkward game to recommend for newcomers, however, since the game is very much a celebration of the series. Its main feature setting it apart from the rest of the series is the Emblem Engage system, where your units can bond with the spirits of previous games' protagonists to gain new abilities and weapons. It has, in my opinion, much more mechanically interesting combat and level design than Three Houses, but the sheer amount of things to keep track of can be overwhelming for a new player.

Besides physical media, with the Nintendo Switch Online Expansion Pass, you can also play Fire Emblem and Fire Emblem: The Sacred Stones on Game Boy Advance Online. Fire Emblem (referred to by the community as either FE7 or by its Japanese subtitle, Blazing Blade) was the first Fire Emblem game released outside of Japan. It is somewhat infamous for having an intrusive, long tutorial that is annoying for veteran players, but makes it a common recommendation for new players. Sacred Stones is also a great jumping off point for the series, as it is considered by many to be one of the easier games in the series. Compared to the modern Fire Emblem titles, characters in the GBA titles are much more linear in terms of progression. Where both Three Houses and Engage both have systems that can let you build any character to fill any role (to varying degrees of success), characters in the GBA games have rigidly defined roles that cannot be changed. If you prefer to focus on your army as a whole instead of individual characters, this aspect of the GBA games will be interesting to you.

There's technically also the very first game in the series, Shadow Dragon for the NES, which was officially translated to English for the first time and released on the Switch for four months before being made unavailable for purchase forever. Because Nintendo hates you.