Adult son joining me in Taipei for more than 6 months

My U.S. resident adult son is talking about coming for a stay. He may want to stay for more than 6 months. What are his options? Will a JFRV be possible? If so, what will I need to do from here to facilitate that objective. I am about to start the process for my Residency Visa based upon length of residency. Will it be possible for him to later join me on my Resident Visa if he decides to stay. He doesn’t have a degree so teaching is out. He is a semi-professional drummer and is wondering about the possibility of doing a little work in that area while he is here but it isn’t required as I can afford having him here. If he does decide to work, what other options would be open to him, conveniently. His primary objective is to visit and tour Taiwan. I understand that a 6 month tourism visa might be possible from TECO. Maybe that’s his best option. We would like to choose wisely as his objectives may change once he gets here.
Thanks for any suggestions.