Rather than money one can donate NTP servers to the pool. [1] It can be a fun learning exercise in setting up a stable stratum-2 time server. One can create graphs from the optional logs.
Why bother? Many of the rabbit holes one could venture down in learning to set up a stable time server can also benefit application servers in terms of latency, responsiveness, learning how to get clients to share resources and so much more. Rather than trying to find cooperative stratum-1 servers, one can start by using each of the Google, Facebook and Apple public stratum-1 servers [2] to get started. They get beat up a lot but most of them are stable most of the time.
Ask your favorite LLM how to set up a public NTP server using NTPD or Chrony. For extra credit play with each of them.
[1] - https://www.ntppool.org/en/join.html
[2] - # grep -E "facebo|goog|appl" /etc/hosts
17.253.16.253 time.apple.com
129.134.28.123 time1.facebook.com
129.134.29.123 time2.facebook.com
129.134.25.123 time3.facebook.com
129.134.26.123 time4.facebook.com
129.134.27.123 time5.facebook.com
216.239.35.0 time1.google.com
216.239.35.4 time2.google.com
216.239.35.8 time3.google.com
216.239.35.12 time4.google.com replies(3):