I would lean towards either a DS, or switch emulation (using a device such as the Steam Deck, so games that require gyro input such as Super Mario 3D World - can still be played fine)
The DS is really affordable second-hand, and the usual third party SD card carts work just as well. People seem to really like the XL models, so may be worth considering one of those
As for the Switch, you’ll likely be able to play your existing physical carts in 20 years time. It’s still Nintendo’s latest console though, so there’s no telling what they may decide to do in future. I think if you have a jailbroken switch you could be in for a difficult time if newer carts use different hardware encryption keys that require a newer firmware…
With emulation though you get to actually own the games and play them on whatever device you want, at any time. The Mii maker and gyro setup does require following some guides to get going, but this stuff is well supported for the Deck (probably similar story for the alternative Windows handhelds but haven’t checked). Yuzu’s early access Android app already has gyro configured, using the sensors built into your phone. Lastly you can do multiplayer with other Yuzu players over the internet, completely independent of Nintendo’s online functionality