Lunging, squatting, push ups, some sort of hip hinge (bodyweight good morning for example - https://www.youtube.com/watch?v=fQ2olCTc0-c), bridges, and supermans should be enough to get you started. Toss in some sort of ab routine (side planks, hard style planks, and something to hit your lower abs like kicking your legs out and bringing them back in) and a trip to the pull up bar (start with dead hanging from the bar, progress that to jumping up onto the bar and slowly lowering yourself down before progressing to a full pull up) every time you get up to go to the fridge / bathroom and you have a good routine to get started.
There are progressions to the superman that will help you out with the pull up. At the moment I'm seeing a lot of home-made content around grabbing a towel and using that to create tension in the superman. Grab the towel, pull it apart, and raise off the ground. You'll eventually want to start to pull said towel over your head to engage your back (which is what helps get you strong to do a pull up.)
For the ab routine portion of your program I like 5-ish minute abs - 30 seconds of work with 10 seconds of rest between each exercise. You do each twice.
You can play around with the reps / timing for everything. Since we're all currently in quarantine I'd do a little bit throughout the day, you'll get more time under tension and you'll get way more reps done throughout the day without the negatives of lactic acid buildup in your muscles.
Example - wake up and do a few pushups, squats, lunges, etc. An hour or two later do it again. Rinse and repeat throughout the day. Do the dead hang / negative pull up / pull up every time you walk by the bar. The goal here is to not wreck your body or feel truly sore afterwards.
Base the number of repetitions you do throughout the day on how you feel the next day / at the end of the week. If you feel sore you're doing too many. Without knowing your current baseline it's impossible to give you a strict number to adhere to.
[addendum]
If you currently aren't able to work from home or you're reading this after the quarantine is over, you most likely can't take breaks every few hours to do some squats and push ups. In that case, pick a time of day to go through the routine of lunges, squats, push ups, etc and do them at least 6 times a week. Could be before work, during a lunch break, after work. Doesn't matter the time just pick a time. There are a ton of apps available to get started on both a squat and push up routine. Download one and figure out where you're currently at physically in relation to what the app is suggesting you do (ie if you can do 20 push ups on your own currently you'd want to start on day something or other where you're starting at 15-ish push ups) Then download the one for squats as well.
The reason you want to be doing 6 days a week with bodyweight is because you're trying to establish a new mental routine. If I suggested 2x or 3x a week there's the possibility Tuesday's workout would turn into "I'll do it Wednesday" then come Wednesday it also doesn't get done. If you're doing something daily you can't put it off to tomorrow because you already have to do it all over again tomorrow.
Regarding No Pain No Gain
With bodyweight exercises the likelihood of feeling incredibly sore will be lower than that of using weights. If you're totally decommissioned you'll feel something but the difference between doing say 30 bodyweight squats versus 40 the next day will be minimal. The difference between 5 heavily loaded squats vs 7 heavily loaded squats in the future will be easily felt. My suggestions are to create a program that's maintainable for as long as you enjoy fitness. Starting off overtraining will lead you down the road to overtraining. Overtraining turns into missing days of reps (so less total reps throughout the week because of additional rest days) OR compensating during exercises to avoid the pain caused by muscle fatigue. I personally have actually done this while kettlebell training - I overtrained my abs then taught myself how to disengage my abs during a kettlebell swing to get reps. This was terrible and something I don't want others to do or repeat. You should do an exercise to get the benefits of every muscle involved in said exercise. If you do something just to get the reps in without the benefit of the exercise you're leading yourself down the path of bad form / injury / and muscle imbalances.
Things like split sets exist where you'd do something like upper body 2x a week, lower body 2x a week, then maybe an active recovery day, a cardio only day, then a total rest day. But that too is down the line.
