I don’t want to be alarmist/buzzkill, but I’d advise getting farther along on your riding before riding outside.
I’m not saying you will never be able to do it, I’m just saying that riding outside is a thing where you go away from home, or your vehicle, and you are supposed to make it back.
I started my fitness journey at over 260, and barely able to run up a flight of stairs. Riding outdoors was excruciating and I was walking it back too many times. I started using the exercise equipment I had already bought, and surprise, in a year of so I was way more fit, and had lost around 50 pounds. I felt better, and riding wasn’t such a daunting thing. But I kept going indoors, we had a LeMond Revolution, a Stairmaster, a TRUE treadmill, and a BoxFlex, and I did have to find places for all of the stuff piled on each one, but kept at it. Doing 5 minutes on the stepper to start out at level 3 as I remember. Walking for 5 minutes on the treadmill, no resistance spinning on the bike. I eventually got to a good place and riding outside was a joy. I didn’t feel like I might have a crises on a ride, and I got better.
Build your base, build your endurance, do the low impact rides on the Peloton, progress to the power zone endurance rides, build on those first, until you feel they are fine (which could be now?). You are starting from a disadvantage, and a rough medical history. Getting stranded, and discouraged, or injured, on an outside bike ride is going to set you back possibly farther.
But since you are on TrainerRoad, I’d suggest that if you are going to buy a bike, you also buy a smart trainer, and ride that combo for at least 6 months and reevaluate the progress, and keep in touch with your physician(s). I have also had some medical setbacks, but talked to my docs and worked on that base, (and blocking them from my Strava) but I am making great progress. It’s taken a long time, but I’m not a youngling anymore either. Be good to yourself. Take your time… Hope this makes sense.
I applaud you for getting busy. I knew someone who shutdown after they had a stent put in. I mean, it IS a big deal, but people with them still lead active lives.Not saying that wouldn’t freak me out, but still… Live to ride, ride to live…