According to the mishna on 25b of Masechet Megilla, "בני העיר שמכרו רחובה של עיר לוקחין בדמיו בית הכנסת" (if the people of a city sell an open area, the money is used to buy a synagogue). The explanation is (as taken from Rashi and summarized on the sefaria site, "the town square, which was at times used for public prayer and therefore attained a certain degree of sanctity, may use the proceeds of the sale only to purchase something of a greater degree of sanctity." This follows the principle of ma'alin bakodesh (we raise things in holiness and don't diminish them) as pointed out by the rashi on 26a.
The gemara clarifies that this doesn't apply to the town square which is only used occasionally for prayer (rashi, eino tadir, or as the Steinzaltz writes, "ולא בקביעות") and this is codified in halacha in the Rambam (Hilchot Tefilla, 11:21) who adds an additional reason (as mentioned by the Ma'aseh Roke'ach, "טעם זה שכתב רבינו לא נמצא שם בגמרא"):
וכן בתים וחצרות שהעם מתכנסין להם לתפילה--אין בהן קדושה, מפני שלא קבעו אותם לתפילה בלבד, אלא עראי מתפללין בהן, כאדם שמתפלל בתוך ביתו
because they have not been set apart for worship but are only so used casually, just as a man prays in his own home
source, italics mine.
The Shulchan Aruch (O"C 154:1) explains "פירוש דרך מקרה והזדמן לא דרך קביעות" that these yards are used via happenstance and are not consistently set as prayer places.
[the mishna b'rurah and other commentators seem to address our courtyards and such as possibly having some measure of holiness if they are used consistently but I don't see a clear statement]
During this pandemic, though, community back yards and other areas, are being designated for outdoor davening on a regular basis. Certain back yard spaces are effectively established for daily and shabbat davening, with chairs and mechitzot left arranged making the space more permanently a prayer location, and the spaces have been used consistently (and almost exclusively as prayer spaces) for months on end. It seems that the davening there became the rule, not the exception as a fixed and established community practice.
Would this affect the homeowner's ability to sell the house and use the money for anything not raising the money in kedusha like buying another private house?