What dos the group do that you feel is specific to 'boomers', OP?
If I were looking for a new group to join, I would be very put off if I were bing judged by my DOB. Age group can make a difference - I joined the WI at 28, as a neighbour invited me. We had just moved house and I thought it would be a good way to met people. Everyone else was in their 60s and 70s, and I left. I worked full-time and they were all retired, so I couldn't join in a lot of the activities, and the focus of their lives was very different from mine. That was fairly extreme, though.
Other than that though, the groups I belong to are multi-generational, and that is what I like about them. I don't want to only hear the voices of older women. I like groups that include men and people of all ages to get variety of experience and lifestyles.
I think that raising the pension age for women has made a big difference to social groups though. I retired at 57, and found that most groups were made up of people more than ten years older, as women of my age were still working. I went back to university for a while, to study a degree in a subject of interest amongst people from 21-70+, then rejoined the local social scene after Covid lockdowns ended.
A lot isn't so much about age, but availability. If you want to attract different age groups, I would drop the 'GenX/Boomer' nonsense, make the meetings accessible to people who work, stop charging annually, so people can drop out if they have grandchildren in the holidays and so on. You haven't said what you mean by 'tech savvy', but unless you are a spreadsheet appreciation society or a gaming group, you might look at things like using WhatsApp groups for communication (rather then email), as it's immediate, and setting up a FB (or similar) page where people can post relevant things for everyone to see I'm thinking of things like articles about the book you are reading if you are a book club, or links to relevant local events if you are a history society etc. No technical knowledge necessary, but using platforms that are free and readily available if you aren't doing so already (although most Boomers are more than au fait with that sort of thing).