Polite way to ask for money instead of gifts?

Hello!

My wedding is about little over 10 months away and I’m working on announcements/invitations. I went to a wedding last year and on their invitation they asked for donations to their first home fund instead of gifts. They didn’t have a registry. I really liked this method of gift giving. Especially considering my fiancé and I have lived together for about 4 years now, have no idea what we’d put on a registry, and are currently renting. As a guest, it was easy to just pass over the money I would’ve used on a gift anyway. Less fuss, in my opinion. But I just mentioned it to my mom and she said it’s kind of tacky/trashy?? I did some web surfing and found a lot of hate towards the idea. I’m wondering if it’s now a dated opinion?

What are your thoughts? If you’re in my boat, what would be a polite way to ask? I wish I saved that invitation 😅

TIA!