Let's say I happen to find myself outside of earth's atmosphere [right at the Kármán line 100km up] one night and don't wish to cause a fuss as I descend to my home. I am stationary in regards to the dirt beneath me. Could I inflate a transparent non-reflective balloon of sufficient size say 1 million $m^3$ with hydrogen and descend into the atmosphere without glowing or causing a sonic boom, landing in my backyard using my impeccable ballooning technique? Releasing gas as needed.
You'd be better off simply using a parachute.
You're not in orbit, you're just very high up, there is a big difference.
Because of this, you're not going fast enough, nor will you get going fast enough, to burn up while you're falling.
The highest skydive thus far was done by Alan Eustace in 2014. He detached from a balloon at over 41 km up and after falling for a rather long time, he opened his fairly standard parachute. As @2012rcampion calculated in the comments, you'll probably want to use a drogue, just like Alan did for his jump. These are commonly used for tandem parachutists for stability and slightly increased drag; they're not hard to come by.
If you're an experienced parachutist, you can make some pretty tricky landings in very small spaces. You won't need to worry about bringing along all that lifting gas and a massive balloon. Just a regular parachute.
As for the stealthiness of the entry, this is the entire goal of HALO jumps. You might call yours a VHALO (Very High Altitude, Low Opening) jump. Using similar techniques, you can make an incredibly stealthy entry into your home country. As stealthy as military research can make you.
In a typical HALO exercise, the parachutist will jump from the aircraft, free-fall for a period of time at terminal velocity, and open their parachute at a low altitude. The combination of high downward speed, minimal forward airspeed, and the use of only small amounts of metal helps to defeat radar and reduces the amount of time a parachute might be visible to ground observers, enabling a stealthy insertion.
Samuel has covered this pretty well, a stealth re-entry is just fine since you're not in orbit. It is the orbital speed of many many thousands of mph that causes most of the problems when re-entering the atmosphere.
The main problem you will have is that there is no atmosphere to slow you down for the initial parts of the fall, this means that you will not have any terminal velocity to speak of.
Fortunately the atmospheric pressure is increasing gradually so use of a correctly sized small parachute should allow you to decelerate as the atmosphere thickens, what you don't want to do is hit the atmosphere at supersonic speeds and start overheating and/or creating sonic booms.
Once you've reached the atmosphere proper ditch the drogue and do a standard free-fall to HALO insertion to reach your target in a manor as stealthy as your parachutes will allow.
If you're descending from Earth orbit at say, 17,000 mph, your large balloon (assuming it can take the reentry forces) is still going to heat up the atmosphere into a fiery plasma as it trades velocity for heat, and it's still going to go 'BOOM' because it's travelling faster than sound. It might be a sharper 'BOOM' rather than a 'BABOOM' that a more conventional reentry vehicle would make.
If you want to make a quiet reentry, you need to slow down to below the speed of sound before entering the atmosphere. Then you can make a nice quiet landing, maybe slipping into a general aviation flight pattern. You'll need extra long skirts on your rocket exhausts, to mask the flare of the engine.