Most parents will say it gets loads easier after those first few years. Poor sleep makes everything harder.
It gets better.
On the rare times he's been sick I stay home and take care of him, and don't even pretend to work. Too much "Daddy play with me", "Daddy look at this", etc. Even if he's basically sofa/bed-bound and sleeping all day I can't work.
At least in Finland we're allowed to have 9ish days of paid leave a year to take care of a sick child.
Totally feel you re side projects and learning new stuff though. There’s just no time and very little will. You need to find new ways to be effective with your time and energy, which can include making tough decisions about where you prioritise both.
Hang in there dude!
It's not easy, but I love them.
Btw, my kids are 5 and 7 - to those of you with <4 years old kids, don't lose hope. As they grow and get more independent it gets easier. You'll have more time to get back to your side projects.
Look at this situation from the bright side - you are there for them now, when they need you the most, when their personalities are formed. Enjoy every moment, it will pass quicker than you think. Before you know it they'll be kicking you out of their room. And you'll be sad about it. ;)
Things that have worked for us...
With the kids... family walks and car rides.
After bedtimes... grown up dinner + korean dramas. wine.
We also have a couple games that are fun when we can sneak them in - 5 crowns (5 suit rummy card game), star crossed (2 player role-playing game that uses a jenga set), lots of trivia couples betting (no fact checking to see who is right about something without making a honey-do bet about it)