thanks for all your comments - in my opinion it has been solved in the second statement by @ed01106 which opened my blind eyes ;-) - there is this possibility on lichess:
maybe a bit more precise:
1. Go to "tools"-menu, then choose the analyse board: lichess.org/analysis
2. Do the first moves to define the opening - in this example the intro to the Smith-Morra Gambit: 1. e4 c5 2. d4 ...
3. On the analysis board on the right you see the 3 different databases ("masters" - "lichess database" - "player") - click "player" and choose "as white" (in this example cause the S-M Gambit is an opening with white) - and you'll see all your games with this opening as white.
4. And if you don't see the databases - click on the book-icon and you'll see it :-)
Best regards - errdee
maybe a bit more precise:
1. Go to "tools"-menu, then choose the analyse board: lichess.org/analysis
2. Do the first moves to define the opening - in this example the intro to the Smith-Morra Gambit: 1. e4 c5 2. d4 ...
3. On the analysis board on the right you see the 3 different databases ("masters" - "lichess database" - "player") - click "player" and choose "as white" (in this example cause the S-M Gambit is an opening with white) - and you'll see all your games with this opening as white.
4. And if you don't see the databases - click on the book-icon and you'll see it :-)
Best regards - errdee