Never encountered advertisements using AdGuard with Vivaldi. I listen to many podcasts there; no issues. On Android, I sideloaded a modded YouTube app without issues. Besides, I can use Kiwi Browser with specific extensions to allow YouTube to play in background and screen switched off, and uBlock origin to block advertisements. If the Chrome manifest does take over, AdGuard on Android does its job perfectly (side loaded). I haven't touched the official applications or use Google Chrome because it's restrictive. I don't use iOS, but Adguard for iOS can filter out advertisements.