I know you’d like to hear from other parents, and I hope they’ll respond. I am an academic language therapist teaching Sounds in Syllables and I meet students both online and in person. I do prefer in person, but I have to say I don’t see a difference in the child’s learning. The work is the work, whether you have a screen between you or not.
Some kids can’t do online, though. Some kids can’t control their behavior as well without someone in front of them in the flesh, and other kids just really dislike it, for all the reasons we adults dislike Zoom meetings or whatever.
Depending on where you are you may be able to find a therapist who will do in person if you want to do a little more searching. I know I have in-person openings (MD burbs). If it is really important and you can’t find someone in person now you can also wait and do the summer intensive. I would not wait in your shoes though - online, even if it isn’t perfect, is better than waiting for a 9 year old.
Maybe give it a try? If it isn’t a fit you can look for an inperson therapist to transition to if needed.