Looking for answers to simple Minecraft questions

Hi folks,

I introduced my daughter to Minecraft and we have both been playing a great deal on my PC (on Bedrock). I enjoy survival and creative modes but she is more into creative mode. I've just ordered a Steam Deck and am planning to install Minecraft on it (as I have learned, it would be Java which is fine). Here's what I was wondering:

I'd like to try playing multiplayer with her, each with our own character, and play together (one of us on the Steam Deck and one of us on the PC). We have not played at all online (she's only 7) and I am inexperienced with servers so forth. I'm looking for some advice on what the best setup is. Do we each need our own Minecraft account? Do we need to play on Realms or something like that? I'd like for us to be able to play creative or survival together. Is there some easy cool way to play together over the home network, sort of old school LAN style? Ideally I'd like for us to play alone together (I'm not ready to have my 7 year old daughter socializing online, I think).

Here's a blocky Santa she made last christmas! I hope this post is not painfully cringe or newby.