Greetings, first-time remote worker!
I've been working remote for 22 years. Some of that was from my home, and some was from a small office I rented on my own. I wouldn't trade it for working in an office; I'm not sure I could.
Given that, I have a few suggestions on ways to make your time of involuntary WFH more tolerable. Here's a few basics. They may sound pedantic, but really they are what has allowed be to be productive despite working in the same building with my sweetie and pets.
First, set up a designated work space. Ideally this is a guest room or something, but it could be a corner of the living room behind a wardrobe screen (that was, in fact, my first "office"). For some of you, it will even be the dining room table between certain hours. Regardless, it's critical that you have a space called "work space" to allow you to get into a work mentality when you're in it. This can also help with other family members trapped at home with you; you can ask them to not approach you when you're in your work space (this works indifferently with kids and not at all with pets, but can help with teens/adults).
Second, try your best to set up a reasonable "desk" in that space. If you have access to an external monitor and/or keyboard, don't work off your laptop. It's terrible for your back. If you're stuck with the laptop, consider something like a Roost or Samson laptop stand or one of the knockoffs, to at least hold your laptop at eye level. Also find a chair that lets you sit upright. This means if you don't have a space you can leave things in, you'll need to set up and tear down every day, but that's actually a good thing; it'll help you establish a routine.
And that's the next thing; despite being at home, you need to lay out a regular schedule of "going to work" and "leaving work." This should include planned lunch and coffee breaks, just like you're in a shared office. It may seem silly to have a scheduled lunch break when you're working off the kitchen table, but it's really necessary for your mental and physical health; otherwise, you'll either forget to eat or snack all day. Believe me, I know. At least you've just eliminated your commute, so you can sleep a little later.
The other big thing you'll miss in an office environment will be the social interaction. The way to bridge this is chat and video. First, have all your video meetings with cameras on so that you actually see your coworkers. Don't be afraid to have some social chatter before or after the official meeting; after all, you would do it in the office, so there's every reason to be social on video. Then, get some kind of online chat you can share with your team, office, or department. This both replaces some social interaction, and also replaces the quick questions of "Hey, Bob, what was that project we did last October, again?"
Do consider what background you're going to have for video calls. This is where having a screen or curtain can help a lot. Otherwise, work in the corner so you can have a wall behind you.
Now, getting dressed. I know some folks who actually like donning full business causal to work from home; it helps them feel productive, and if that's you, go for it. For myself, I have a large selection of pyjama pants that I wear with the presentable shirts my coworkers can see on video. Consider investing in some high-quality slippers, you'll be wearing these a lot. Regardless of what you wear, get up, brush your teeth, shower, make coffee ... just like you were going to an external office. If you slide into dishevelment, your work and your relations with your cowokers will suffer too.
Just like you would in an open-plan office, plan to wear some noise-cancelling headphones if you don't have a good work space. They serve the same function at home as they do in a cubicle.
Welcome to the world of remote work. I hope this helps!