Depends on your state and state laws on peace officers. Assuming you are talking about being a reserve deputy and not something like an unarmed Sheriff's Posse or anything lile that.
In TX reserve SO deputies are Peace Officers and attend law enforcement academy (aka police academy) just like any other peace officer and sit for state test same as any other. There are some LE training academics that do evening classes and last longer due to modified schedule vs. M-F 9-5 type training, again at least here in TX. Agencies all handle reserves differently, I used to be a Reserve Police Officer in a small town and we covered shifts same as full time officers, sometimes augmented them but we patroled alone as needed, wrote tickets, responded to calls and made arrests same as any full time officer. I served on our tactical unit too and was on a couple of task forces (warrent and drug TFs over my years of doing the job). We were pretty much treated as equals and we met the same standards as FT officerd and our uniforms and badges did not differ from full time, we just didn't work full time and didn't get paid as employees.
With larger agencies, be that PDs or SOs, you tend to be more of an augment to full timers and are more likely to be looked down on and not as professional's, and definitely not equal to them. It's reality in larger agencies. Some do not allow reserves to patrol or work alone. Certain extra or special duties are off limits like SWAT/Tactical units while others may be allowed or encouraged like bike or lake patrols. All depends on agency and their policies. Also I'm talking TX. Some states don't require you be a sworn peace officer and have a form of lesser license for reserves, some states do not give you peace officer status off duty, so away from on duty work you have no police powers at all. I would do your research and maybe see if you can meet some reserve officers from the SO you are looking at and see if it's what your looking for. If you decide to pursue it, own it and take it seriously as if it were your profession. Be in shape, train and learn your job.
Also i did this in the 80s and 90s. Shit is different now. I would never trust an agency to have your back today. You use deadly force on some doper full of meth and had a fentanyl chaser that tried to kill you and he/she fits a particular demographic you will be the next big news story. Look at the full time cops who have been thrown to the wolves before an investigation is complete and the facts are known later to be completely justified in the use of force. What do you think they will do to some volunteer deputy or cop who is not even protected by employment laws or police unions, if applicable. Yes most cops will never use deadly force but it can and does happen and you do need to consider it could happen to you. To include you being the one injured. I had several friends and acquaintances killed or shot in the line of duty, both reserve and FT. I had a buddy who was a reserve in another small town got shot at one night responding to a domestic violence call he got lucky and was not hit. I was injured a couple of times, cuts and other minor injuries, thank goodness that was all the physical injuries I had, on duty it's workers comp. and stitches heal up quick. Nearly killed once or twice working wreaks and missing being struck by a high speed vehicle by inches. More cops get killed by things like this than what you see on TV that makes the news.
Good luck with what ever descision to make