Margomar, I have no experience of adults with the balloon technique or of adults having grommets put in. I can only say that my son now mid 40s ( how did that happen!) had lots of ear problems as a child and a hearing loss, also needed speech therapy. He had grommets in at age 3 and a half , and the improvement was amazing!!! Grommets made a massive positive difference. He eventually had long stay grommets in, he was 12 before he no longer needed them . His Eustachian tubes were blocked, having Covid has clearly given you the same problem. In your situation I would take the consultants advice and go for it. No doubt you now have a hearing loss so hopefully grommets will address that issue.
My son is absolutely fine now ! Good luck whatever you decide. Let us know how you get on .