GAL sharing between tenants (Exchange Online / Outlook)

Is there a way to share directory info (Global Address List / GAL) between two willing M365 organizations? I feel like it should be as simple as this screen (attached screenshot, Exchange Online Admin Portal menu 'Organization' > 'Sharing', but this is just for calendar info. Where/how would I approach this, other than writing my own customer powershell solution (I've thought about it) or buying some 3rd party or installing MIM or something complicated or expensive like that? I was hoping for something as genuinely simple as this Organization > Sharing menu... just with contact, instead of Calendar only-information (which is only useful if you know the address or information of the user or group you're trying to email or schedule a message with. :)).

I've been googling but not getting very good results. I'm kind of shocked this isn't a feature or common scenario that partner organizations would desire when both on a collaboration platform like Exchange/Teams?  We've all had that scenario where we're like "Who's that new sales rep at orgY?" so we can include them in an email... the GAL is invaluable, it seems. I've been working in non-profit for 25 years and we've had this sort of setup since the first days of Exchange 5.5 and Galsync ~2000. I don't understand why this is a more commonly demanded or available feature, or why I can't find any documentation on this or voice of other customers that would seem to want it (a few posts here and there). 

Any thoughts or experts? Is there an easy way to do this between two tenants that aren't part of the same billing same AAD etc., just orgX.onmicrosoft.com wants to share contacts with orgY.onmicrosoft.com. 

Man, my specificity here tonight makes me realize I've been peer-programming with ChatGPT too much tonight. : ) Have a good night all! (You're not bots) Thanks!