here are more views of my one car garage

Your question is not specific if you are looking for temporary decorations, interior walls but keeping the garage intact in concept, or completely removing the function of garage and it's overhead door and making this a room equivalent to the house proper.

If the roof is a freestanding gable, it looks as if someone removed the rafter ties. Those would be structural and double as creating a flat ceiling.

Are there weather considerations, or does it stay mild year round? Also, do you have a preliminary budget? What about resale considerations-a garage is a handy and desirable feature for most people, so would you be willing to keep the door so it could be turned back into a garage with a minimum of work when and if you sell?

@armjim - it stays mild year round, i will get a small window unit for interim fix until i can splurge on a mini split. yes i would definitely keep the garage door. those are my thoughts exactly. have it be a comfortable office for added living space, or easily turn it back into a garage if desired in a resale scenario!

it’s actually a super small one car garage so even my car barely fits. i am going to build a small shed in the backyard to house all my tools (which i don’t have many of)

i am stumped on the best way to hide this since the ceilings are so high.

Your dryer exhaust arrangement is horrible.

@dadoes totally agree, how can i improve it?

Get rid of the flexduct. The internal coils cause drag/obstruction on the airflow, turns and sags make it much worse. Use rigid/solid metal ducting, as straight as possible with adjustable elbows for any turns/curves that are absolutely necessary.

Your equipment looks to be Maytag. Installation instructions state that maximum length for flex duct with the coils fully extended and no turns or sags is 7-3/4 feet (93 inches). Every 90° curve is equivalent to 5 feet of length for any kind of ducting material. 45° is 2.5 feet. You have one curve that looks to be a 180°.

27 feet is maximum length for rigid/solid ducting with four 90° turns. A 90° turn at the exit on back of the dryer is considered as part of the count.

Do you live in an arid area? If not, you are going to need to consider air management. Humidity is no friend to electronics and much furniture. You may or may not need heating or AC, but you will for sure need something to deal with the humidity of a garage. Air movement might be a thing too if you only have the one window- you aren't likely to want the garage door open all the time. What do you have planned for additional lighting in there?

You could use drapes as a room divider.