I also do not have an extra old laptop that I can use as an alternative airgapped wallet.
You can just buy an old cheap laptop with the said characteristics as mentioned in this thread:
[Guide] Secure air-gapped crypto wallet storage method. Or just ask someone you knew maybe they have some.
How about Mycelium? It is easy to install and security is decent. I was using Mycelium before I purchased my Trezor (which is worth it in my opinion) which was a very long time ago and never have I encountered any issues all those times.
On my coins.ph account, I just store enough to spend it on buying a load, paying bills and occasionally use it to convert my cryptocurrencies into PHP. You can read in the local thread how hassle it is to store huge amount in coins.ph and I don't want to undergo such a thing.