The only thing that really makes me feel unsafe with paper backups, is the fact that the ink could fade after 20-30 years.
Yeah, paper backups can be a convenient and easy way to store important information, but their durability can be a concern. Based on my experience, prints from an inkjet printer can become unreadable much sooner than the estimated 20-30 years, and this can vary depending on environmental conditions. To mitigate these risks, it is a good idea to use archival-quality paper which are specifically designed to last longer and resist fading. Additionally, in general, laser printers and their toner-based output offer longer lasting prints compared to inkjet printers.
The problem is, I don't want to use a printer.
2-3 years is still a decent time frame and you would be able to forsee any possible damage to the paper or visibility issues. Paper is more durable than most think and can last quite a long time if kept in a suitable location.
My seed phrase is handwritten, in black ink, totally hidden from the sunlight, inside a deck card sleeve and inside a box, protected from moisture.
The most easiest way I have done this is via my ledger and one smart phone which is only turned on when I need to take out my bitcoin and spend them. So ledger everyone knows it as hardware wallet, you need the passkey and phrases and stuff. However, sometimes the security of your funds can be managed with simple tricks rather than getting too high techie about it! I have Mi phone which is old and I am no longer using it since 4-5 years now. Since then I have formatted it and only have mycellium wallet installed on it. Now the address is mostly used to fund it and I rarely withdraw anything from it. I have kept that phone turned off and locked up in my desk. I only take it out now and then when Mi releases any software's and mycelium updates etc. So far I am doing great, and it serves the purpose of security perfectly.
I guess this means that your mobile is not connected to the internet, is it ? I don't claim there is an issue here, I am only saying that this is actually a hot-wallet if it connects to the internet. However, I agree that your usage seems to be very safe, compared to someone's that would use their mobile for everyday tasks.