Thank you for sending the link to the terrific Shi'ur. Yes, I heard, from 34:40 until 35:30, that Rav Elefant cites Mefarshim who teach that a Segulah for preventing poverty is to daven in a shul. Since you mentioned Tefilah b'Tzibur, I will just mention that the Rav added, if I heard him correctly, that this virtuous practice is advised even if there is no Minyan available.

I hear you are asking for Segulos that will help overcome not just poverty but childlessness, which is by no means any less of a difficult hardship. It is a very important issue you are raising. This is a terribly distressing issue for many couples. I came across a number of suggestions, and although it is not for me to rank them, I will try to list them roughly in order, beginning with those which seemed most traditional. I believe that many of the items I will mention you are already aware of, so forgive me for that, but I hope that some of the ideas are new.

1) Tefilah. In Yevamos 64a, Rebbi Yitzchak explains: Why were our Avos originally unable to bear children? Because ha'Kadosh Baruch Hu desires the prayers of the Tzadikim. Hash-m may withhold children from a person for many years because He wants the individual to strive in prayer.

2) Hishtadlus, such as seeing a fertility doctor. Many treatments are available today, and I know individuals who have waited 8 or 10 years, but with great Siyata d'Shmaya they were blessed with healthy babies after a series of treatments. Bonei Olam is an organization that helps with the financial aspect of these treatments. Their website is https://www.boneiolam.org .

3) Davening for another person. Chazal say that if we pray for someone else who has the same hardship, e.g. they are also childless, then Hash-m will grant us the Yeshu'ah first. The Gemara (Bava Kama 92a) learns this from Avraham who prayed for Avimelech and subsequently Sarah was granted a son even before Avimelech was healed. There is a wonderful organization called Kol ha'Mispalel which operates on this principle; they anonymously match up pairs up individuals undergoing the same Tzarah to pray for each other. I believe they can be contacted by email at connect@kolhamitpalel.com or by phone at 646-294-4355. Another organization based on the same idea can be found at the website https://davenforme.org/.

4) Observing the Mitzvah of Neros, as Rav Huna says (in Shabbos 23a), "ha'Ragil b'Ner will have sons who are Talmidei Chachamim."

5) After a woman lights the Shabbos candles, she can recite the Haftarah of the first day of Rosh Hashanah -- the verses from Shmuel (chapter 1) which tells the story of Chanah's struggle being without any children until the eventual birth of Shmuel (Kitzur Shulchan Aruch 72:2).

6) Perform the Mitzvah of Hachnasas Orchim, providing hospitality for guests. The Midrash says that this is a merit for which Sarah Imeinu and the Shunamis woman were each blessed with a child (Midrash Tanchuma, Ki Seitzei 2).

7) Being the Kvater at a Bris (Otzar ha'Bris 12:9).

8) I also see other suggestions in the name of Rav Moshe Shternbuch (see Teshuvos v'Hanhagos 1:790): the husband can bathe in very cold water before intimacy; ask a Kohen to mention one's name before he performs Birkas Kohanim; ask a Mohel or Sandek to pray before a Bris; recite Pitum ha'Ketores from a Klaf twice a day; to fast on four separate days; and to change one's name.

9) There are many more, but for now I will leave you with this link which includes a series of additional Segulos: https://www.betterthanasegulah.org/free-services/segulos/segulos-for-zera-kayama/

I hope this helps!

Warmest regards,

Yishai Rasowsky