I actually started bike commuting when I was training for a triathlon and had the realization that made more sense for me to have my bike with me than to take the bus home, then get changed and go out for a ride. Started bike racing a few years ago, and have incorporated commuting into training pretty consistently since. I’m a Cat 3 on the road and I know a lot of racers who commute, at least pre-pandemic and WFH. There are only so many hours in the week, and you have to get saddle time where you can.
So, a couple things. First, remember that there’s no rule that says you have to take the most direct route between home and work, so add miles or find a route that’s on better roads, however you define that. Second, it helps if you have a place to change at work, even better to have a shower if you’re planning to do the hard riding on the way to work.
As for the kinds of workout rides, I’ve done them all from sprint to vo2max to sweetspot to recovery rides. I typically follow a plan that I have put together, sometimes with coaching help. I ride my race bike and bring stuff in a backpack, so really high effort stuff like sprint work out of the saddle isn’t great with a backpack swinging around, but generally the longer the intervals, the better. . 2x20’ sweetspot intervals are fine, if you can find a detour that avoids a lot of intersections.
So yeah, it’s totally doable and a really efficient use of time. Even if you don’t go in for a structured training program, you’ll get fitter just by riding longer and more consistently through the week. Good luck!