The first Trainer Gallery card has been revealed in English
The official pokemon website has revealed the English versions of Shaymin VSTAR, Boltund V (Trainer Gallery), Simisear V, Luxray & Kindler from Sword & Shield - Brilliant Stars that is releasing next month on February 25, 2022.
They have revealed the first Trainer Gallery card for this set, which appear to be based off the Japanese CHR/CSR cards from VMAX Climax. Boltund V is a Character Super Rare (CSR) in VMAX Climax. It's numbered TG13/TG30. To give you an idea:
VMAX Climax has 101 SR/CHR/CSR/UR cards total, with 28 CHR and 42 CSR cards alone in that set. It's safe to assume, all the CHR/CSR cards won't fit in this Trainer Gallery subset (that seems to be a 30-card subset) in Brilliant Stars.
Prereleases of Brilliant Stars are starting from February 12, 2021, so the first set of 2022 here is closer than you might think.
You can check the Japanese S9 Star Birth Set List & S8b VMAX Climax Set List to have an idea what (unrevealed) cards could be in our Brilliant Stars set.
Update 09-02-2022: Trainer Gallery cards of Umbreon V, Umbreon VMAX, Sylveon V, Sylveon VMAX have been revealed. Also Whimsicott VSTAR, Garchomp & Cynthia's Ambition.