I personally won't be replying to these OTRS tickets for obvious reasons, but a few users have suggested a donation link inside the app:
https://ticket.wikimedia.org/otrs/index.pl?Action=AgentTicketZoom;TicketID=7710367
https://ticket.wikimedia.org/otrs/index.pl?Action=AgentTicketZoom;TicketID=7913393
https://ticket.wikimedia.org/otrs/index.pl?Action=AgentTicketZoom;TicketID=7944272
https://ticket.wikimedia.org/otrs/index.pl?Action=AgentTicketZoom;TicketID=8008528
https://ticket.wikimedia.org/otrs/index.pl?Action=AgentTicketZoom;TicketID=8031015
https://ticket.wikimedia.org/otrs/index.pl?Action=AgentTicketZoom;TicketID=8037059
https://ticket.wikimedia.org/otrs/index.pl?Action=AgentTicketZoom&TicketID=8077451
I expect that this would be just a link to the donation web pages, rather than handling any details about donations inside the app (which sounds scary).