We actually have many examples of Judahite seals (or rather, impressions or stamps made by those seals).
The so-called LMLK seals (after the letters lamed-mem-lamed-kaf, which could be read as le’melek “to/for/of [the] king”) were stamped on the handles of large storage jars found mostly in and around Judahite sites like Lachish or Jerusalem. None of the original seals have been found, but about 2,000 impressions (or stamps) made by at least 21 seal types have been documented. What makes them interesting is that many of these seals bear the image of a four-winged scarab beetle or a two-winged solar disc, with one of four place names (Hebron, Mamshat, Socoh, and Ziph) inscribed underneath. Other seals bear personal names (which could be that of royal officials).
Winged solar disk with ‘Hebron’ over it
Scarab version of the Hebron type seal
Jar handles stamped with personal seals and incision marks have also been found. (Other examples of personal seals here and here.) So far, the exact purpose of these seals remain unknown and there are many theories that try to explain their original function, although they are now often associated with the reign of Hezekiah (reigned c. 715-686 BC).
Speaking of Hezekiah, we actually have his seals.
Impressions of two of Hezekiah’s seals, bearing the inscription: “Of Hezekiah, (son of) Ahaz, King of Judah”
You would notice that many of these seals have the solar imagery (the winged solar disk and the scarab), which is ultimately Egyptian in origin (although the symbols, especially the latter, were already quite well known in the area around that time, thanks in part to the huge influence of Egypt and peoples like the Phoenicians, who adopted Egyptian art styles). We know from the Old Testament that Hezekiah, seeking to throw off his subservience to the Assyrian kings, entered into an alliance with Egypt during his reign (Isaiah 30-31; 36:6-9), which could explain his use of Egyptian motifs.
But why the solar imagery? One theory is that these are actually symbols or representations of Yhwh, the Israelite God. This is not a very prominent idea in the Old Testament, but judging from some archaeological finds it kind of seems that the association of God (Yhwh) with the sun - even the outright worship of the sun as Yhwh - was a popular idea among pre-exilic Israelites/Judahites.
The closest thing we have to this within the OT is Psalm 84:11/12 “For the LORD God is a sun and shield; the LORD bestows favor and honor.” Not to mention that there are possible solar overtones in certain expressions such as “seeing God,” God “rising,” and God’s glory coming from the east, as well as biblical and extrabiblical names with the elements *šḥr (shaḥar) “dawn,” *zrḥ (zaraḥ) “rise” and *n(w)r (nur) “light.” In addition, the references to God’s ‘wings’ (cf. Psalm 17:8; 57:1; 36:7; 61:4; 63:7) invites comparison with the winged solar disk represented on the above seals - although it could have also been informed with the iconography of the winged cherubim in the Temple of Solomon.
The LORD came from Sinai
and dawned from Seir upon us;
he shone forth from Mount Paran;
he came from the ten thousands of holy ones,
with flaming fire at his right hand. (Deuteronomy 33:2)
“How precious is your steadfast love, O God!
The children of mankind take refuge in the shadow of your wings.”
In fact, in Ezekiel 8:16 and 2 Kings 23:5, 11 you have the criticism of solar worship by priests within the Jerusalem temple (the association of Yhwh with the sun gone awry?):
And he brought me into the inner court of the house of the LORD. And behold, at the entrance of the temple of the LORD, between the porch and the altar, were about twenty-five men, with their backs to the temple of the Lord, and their faces toward the east, worshiping the sun toward the east. (Ezek. 8:16)
And [Josiah] removed the horses that the kings of Judah had dedicated to the sun, at the entrance to the house of the LORD, by the chamber of Nathan-melech the chamberlain, which was in the precincts. And he burned the chariots of the sun with fire. (2 Kings 23:11)
I also recommend this:
Lasting Impressions: New bullae reveal Egyptian-style emblems on Judah’s royal seals by Robert Deutsch