You might want to start out and research if your home town and the "drive-able" surrounding area is enough of a "typewriter town" to warrant an investment of a shop (either in your home or in a retail shop).

If there are not enough typewriter "nuts", it may not be a viable venture.

I have 30+ machines in my collection and since I do not want to make a 8-10 hour 1-way trip to Portland OR or Bremerton WA to access repair shops, I have self-taught and worked on my own machine...sometimes using parts-machines to keep 1-2 other machines going.

Shipping 2-ways to these shops involved $ 70-100+ and risks damage or loss in the shipping process, etc.

My home town had 2-3 shops but one by one they went out of business or the owner retired.  There does not seem to be much of a typewriter-user niche in my home town to keep a local shop afloat.

And I also live right on a major highway where people could see my sign so that would also be helpful.

You would have to live in a major city to even consider it as a full-time business, but even then I highly doubt you would find enough work to keep a brick and mortar operation afloat. In my experience very few people are actually willing to pay someone to repair their typewriter; like so many trades in the internet-era, typewriter technicians (professional, factory-trained) are now undervalued because everyone thinks they can become an expert by watching a few YouTube videos.

Finally (please don't take this as an insult), are you actually qualified to repair typewriters? Do you own all of the specialty tools that you'll need? Are you suitably connected to source parts or fabricate replacements that aren't available? Most collectors and enthusiasts can perform simple repairs, but I'm willing to bet that a substantial number of the jobs you would get would be from those who had already tried to fix their machines on their own - and horribly botched it.

Branch out, get involved in the community, advertise your services.  I work from home very successfully, and post college graduation I'd be working to obtain a physical storefront.  It can be done, and it will be done!